Flux-cored wire for gas-shielded arc welding, method for welding steel for very low temperature use, and method for manufacturing weld joint

Abstract

 [Object] There is provided a flux-cored wire capable of obtaining a weld metal having excellent low temperature toughness and improving welding efficiency, in which preheating performed for preventing cold cracking can be omitted or simplified.
[Means for Solving Problems] The flux-cored wire includes one or more of CaF₂, BaF₂, SrF₂, MgF₂, and LiF and, when a total amount thereof is defined as α, the α is 2.0% to 7.0%, by mass%, with respect to a total mass of the flux-cored wire, one or more of a Ti oxide, a Si oxide, a Mg oxide, an A1 oxide, a Zr oxide, and a Ca oxide are included in the flux-cored wire, and when a total amount thereof is defined as β, the β is 0.2% to 0.9%, by mass%, with respect to the total mass of the flux-cored wire, a ratio of an amount of the CaF₂ with respect to the α is 0.90 or more, and a ratio of the α with respect to the β is 3.0 or more and 15.0 or less.

Description

[Technical Field of the Invention]

[0001] The present invention relates to a flux-cored wire used in gas-shielded arc welding of Ni steel for very low temperature use containing 5.5% to 9.5% of Ni, which is used for an LNG storage tank, a chemical plant, or the like, and particularly relates to a flux-cored wire for gas-shielded arc welding, capable of obtaining a weld metal having excellent low temperature toughness and improving welding efficiency, and having excellent cold cracking resistance, a method for welding steel for very low temperature use using the same, and a method for manufacturing a welded joint.

[0002] Priority is claimed on International Patent Application No. PCT/JP2013/080284, filed November 8, 2013, and Japanese Patent Application No. 2014-220853, filed October 29,2014, the contents of which are incorporated herein by reference.

[Related Art]

[0003] In recent years, there has been an increasing demand for natural gas having less carbon dioxide emissions than that of oil, coal, or the like resulting from tightening of carbon dioxide emission regulations due to problems including global warming, and with the increasing demand for natural gas, demand for constructing an LNG storage tank has also been increasing worldwide. As steel used for an LNG storage tank, in order to meet demand for securing toughness at a very low temperature of -196°C, Ni-based steel for low temperature use including 5.5% to 9.5% of Ni is used.

[0004] In regard to welding for the Ni-based steel for low temperature use, because of the necessity of satisfying rigorous safety regulations, a Ni-based alloy welding material including 60% to 80% of Ni is used. However, since containing a large amount of Ni, the Ni-based alloy welding material is very expensive. Further, since the Ni-based alloy welding material has poor fluidity in a molten state, weld defects such as incomplete fusion is easily generated. In addition, since welding is performed with a low heat input to prevent weld defects, there is a problem in welding efficiency.

[0005] Further, in order to reduce welding material costs, when the amount of Ni is reduced to about 5.5% to 9.5%, which is the same level as Ni-based steel for low temperature use, the weld metal has a very hard martensite structure and a problem of cold cracking arises. The cold cracking does not occur in a Ni-based alloy welding material in which a structure of the weld metal is an austenite structure. The preheating performed for preventing cold cracking is a new problem in reduction of welding costs.

[0006] Under the circumstances, as a welding wire of steel for very low temperature use, for example, the following wires have been suggested.

[0007] In Patent Document 1, there is disclosed a flux-cored wire in which a Ni-based alloy material is used as an outer steel sheath. However, the amount of Ni is 60% to 70% and a welding material cost reduction has not been achieved.

[0008] In Patent Document 2, there is disclosed a welding material in which the amount of Ni is 7.5% to 12.0%. However, TIG welding which has low welding efficiency is employed as a welding method and thus welding efficiency has not been improved.

[0009] In Patent Document 3, there is disclosed a wire which is a welding material in which the amount of Ni is 8% to 13%, and has excellent welding efficiency by reducing welding material costs and applying submerged arc welding thereto. However, since submerged arc welding is employed as a welding method, an obtainable weld metal has 250 ppm of oxygen, which is a large amount, and accordingly, the absorbed energy at -196°C is low. Thus, sufficient low temperature toughness cannot be secured. In addition, any examination of cold cracking as a problem caused in this amount of Ni has not been conducted.

[0010] In Non-Patent Document 1, a technology is disclosed which obtains a weld metal having a low oxygen content at the same level as in TIG welding, by performing MIG welding with a 100% Ar shielding gas using a solid wire of an iron alloy in which the amount of Ni is reduced to about 10%. In this technology, the amounts of P and S in the wire are significantly reduced, thus toughness can be secured. However, in the experiments conducted by the present inventors, there are defects such as a large amount of diffusible hydrogen being included in the weld metal obtained by the method in Non-Patent Document 1 and cold cracking resistance being deteriorated. In addition, since the wire described in the Non-Patent Document 1 is a solid wire in which Rem addition is required, there are other defects of spattering being violent and welding efficiency being deteriorated during welding.

[0011]  Accordingly, as a welding wire of steel for very low temperature use, the development of a welding wire capable of reducing welding material costs and improving welding efficiency, and having excellent cold cracking resistance has been in strong demand.

[Prior Art Document]

[Patent Document]

[0012] 

[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2008-246507

[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. H09-253860

[Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2008-161932

[Non-Patent Document]

[0013] [Non-Patent Document 1] Kazuo Agusa, Masaaki Kosho et al., "Matching Ferritic Filler MIG Welding of 9% Ni Steel", Kawasaki Steel Giho, vol.14, No.3 (1982)

[Disclosure of the Invention]

[Problems to be Solved by the Invention]

[0014] When there is an attempt to obtain a weld metal having excellent low temperature toughness even in a case in which the amount of Ni of a welding wire for consumable electrode type gas-shielded arc welding having excellent welding efficiency is reduced, oxygen penetrating into the weld metal from an active gas included in the shielding gas becomes a problem.

[0015] In gas-shielded arc welding, as a shielding gas, Ar-10% to 30% CO₂ (that is, including 10% to 30% of CO₂ by volume fraction, and a remainder including a mixed gas of Ar), 100% CO₂, Ar-2% O₂, or the like is generally used. 2% or more of CO₂ or O₂, which is an active gas, is included in the gas. This is because arcs are unstable and a sound weld metal without weld defects cannot be obtained by using only an inert gas.

[0016] On the other hand, these active gases are ionized by welding arcs and the ionized oxygen enter the weld metal, and thus, when the active gases are mixed, the amount of oxygen in the weld metal increases. When the amount of oxygen in the weld metal increases, the absorbed energy at a ductile fracture decreases.

[0017] As a welding material for steel for very low temperature use, when a welding material in which the amount of Ni is reduced to the same level as Ni steel containing 5.5% to 9.5% of Ni is used as a base metal, it is difficult to secure the absorbed energy at ductile fracture. Thus, a welding method capable of obtaining a weld metal having a small amount of oxygen is required. However, a welding wire capable of obtaining a sound weld metal by gas-shielded arc welding using a shielding gas in which the amount of an active mixed gas is reduced or using only an inert gas has not yet been realized.

[0018] In non-consumable electrode type TIG welding, a sound weld metal can be obtained and the amount of oxygen in the weld metal is reduced. However, there are problems in that the welding efficiency is very low compared to consumable electrode type gas-shielded arc welding and welding costs increase in the TIG welding.

[0019] Further, since the weld metal in which the amount of Ni is reduced to the same level as Ni steel containing 5.5% to 9.5% of Ni has a very hard martensite structure in the welding material, there is a problem of cold cracking.

[0020] In order to prevent cold cracking, preheating is required. The preheating is also a cause of deteriorating welding efficiency, but in the related art, any examination of cold cracking resistance has not been conducted.

[0021] The present invention has been made in consideration of the above-described problems in the related art and an object thereof is to provide a flux-cored wire for gas-shielded arc welding capable of significantly reducing welding material costs by reducing the amount of Ni to the same level as Ni steel containing 5.5% to 9.5% of Ni, and obtaining a weld metal having excellent low temperature toughness at -196°C even when gas-shielded arc welding having excellent welding efficiency is applied. In addition, another object thereof is to provide a flux-cored wire for gas-shielded arc welding not requiring preheating for preventing cold cracking or capable of significantly reducing preheating, and a method for welding steel for very low temperature use using the same.

[Means for Solving the Problem]

[0022] As a result of intensive investigations to solve the above-described problems, the present inventors have found that when a flux-cored wire in which the amount of Ni is reduced to the same level as Ni steel containing 5.5% to 9.5% of Ni has a slag composition having fluoride as a main composition, it is possible to (i) obtain a sound weld metal in which arcs are stable and an amount of oxygen is small even with gas-shielded arc welding using a pure Ar gas or a mixed gas in which a ratio of oxygen is less than 2% in a pure Ar gas, as a shielding gas, and to (ii) obtain excellent Charpy absorbed energy at -196°C by significantly reducing an alloy composition filled in a flux, using an outer steel sheath containing 6% to 16% of Ni, further reducing the amount of oxygen in a weld metal, and then, forming the most suitable composition for a weld metal obtained by this welding method with C, Si, Mn, and other alloying elements.

[0023] Further, it has been found that the amount of diffusible hydrogen in the weld metal can be significantly reduced by the use of the flux-cored wire according to the present invention.

[0024] Accordingly, the flux-cored wire, capable of obtaining a weld metal having excellent low temperature toughness, achieving high welding efficiency, and omitting or simplifying preheating performed for preventing cold cracking in welding of Ni steel containing 5.5% to 9.5% of Ni, has been found and further investigations have been conducted based on the findings. Therefore, the present invention has been accomplished.

(1) According to an aspect of the present invention, a flux-cored wire for gas-shielded arc welding is provided including an outer steel sheath; and a flux with which the outer steel sheath is filled, in which one or more of CaF₂, BaF₂, SrF₂, MgF₂, and LiF, which are metal fluorides, are included in the flux-cored wire and, when a total amount thereof is defined as α, the α is 2.0% to 7.0%, by mass%, with respect to a total mass of the flux-cored wire, one or more of a Ti oxide, a Si oxide, a Mg oxide, an Al oxide, a Zr oxide, and a Ca oxide, which are metal oxides, are included in the flux-cored wire and, when a total amount thereof is defined as β, the β is 0.2% to 0.9%, by mass%, with respect to the total mass of the flux-cored wire, one or more of CaCO₃, BaCO₃, SrCO₃, MgCO₃, and Li₂CO₃, which are metal carbonates, are included in the flux-cored wire and a total amount thereof is less than 0.6%, by mass%, with respect to the total mass of the flux-cored wire, a ratio of an amount of the CaF₂ with respect to the α is 0.90 or more, a ratio of the α with respect to the β is 3.0 or more and 15.0 or less, an amount of the Ti oxide is 0% to 0.4%, by mass%, with respect to the total mass of the flux-cored wire, an amount of the Si oxide is 0.2% to 0.5%, by mass%, with respect to the total mass of the flux-cored wire, an amount of the Ca oxide is less than 0.20%, by mass%, with respect to the total mass of the flux-cored wire, an amount of an arc stabilizer in the flux is 0% to 0.50%, by mass%, with respect to the total mass of the flux-cored wire, an amount of an iron powder in the flux is less than 5%, by mass%, with respect to the total mass of the flux-cored wire, chemical compositions except the metal fluorides, the metal oxides, and the metal carbonates include, by mass%, with respect to the total mass of the flux-cored wire, C: 0.003% to 0.040%; Si: 0.05% to 0.40%; Mn: 0.2% to 0.8%; Al: 0.003% to 0.050%; Ni: 6.0% to 16.0%; P: 0.02% or less; S: 0.01% or less; Cu: 0% to 0.5%; Cr: 0% to 0.5%; Mo: 0% to 0.5%; V: 0% to 0.2%; Ti: 0% to 0.1%; Nb: 0% to 0.1%; B: 0% to 0.01%; Mg: 0% to 0.6%; REM: 0 to 0.0500%; and a remainder: Fe and an impurity, a SM defined by the below expression a is 0.3% to 1.0%, and Ceq defined by the below expression b is 0.250% to 0.525%,



in the expressions a and b, elements noted in brackets express amounts (mass%) of the elements, respectively.

(2) In the flux-cored wire for gas-shielded arc welding according to (1), the flux-cored wire may include the outer steel sheath including Ni and the flux filled therein, and an amount of Ni in the outer steel sheath may be 6% to 18%, by mass%, with respect to the total mass of the outer steel sheath.

(3) In the flux-cored wire for gas-shielded arc welding according to (1) or (2), an amount of REM in the flux-cored wire maybe 0.0100% or less, by mass%, with respect to the total mass of the flux-cored wire.

(4) In the flux-cored wire for gas-shielded arc welding according to any one of (1) to (3), the amount of the Ca oxide in the flux-cored wire may be less than 0.10%, by mass%, with respect to the total mass of the flux-cored wire.

(5) In the flux-cored wire for gas-shielded arc welding according to any one of (1) to (4), a tensile strength of a weld metal may be 660 MPa to 900 MPa in a tensile test to the weld metal regulated in Japanese Industrial Standards JIS Z 3111-2005 in the gas-shielded arc welding using the flux-cored wire.

(6) In the flux-cored wire for gas-shielded arc welding according to any one of (1) to (5), a slit-shaped gap may exist in the outer steel sheath of the flux-cored wire.

(7) In the flux-cored wire for gas-shielded arc welding according to any one of (1) to (5), a slit-shaped gap may not exist in the outer steel sheath of the flux-cored wire.

(8) In the flux-cored wire for gas-shielded arc welding according to any one of (1) to (7), a perfluoropolyether oil may be applied on a surface of the outer steel sheath of the flux-cored wire.

(9) According to a second aspect of the present invention, a method for welding steel for very low temperature use is provided, in which welding is performed with the flux-cored wire for gas-shielded arc welding according to any one of (1) to (8), and with any one of a pure Ar gas, a mixed gas of Ar and 1.5 volume% or less of O₂ or CO₂, a pure He gas, and a mixed gas of He and 1.5 volume% or less of O₂ or CO₂ as a shielding gas.

(10) According to a third aspect of the present invention, a method for manufacturing a weld joint is provided, in which a steel plate in which a thickness is 6 mm to 100 mm, an amount of Ni is 5.5 mass% to 9.5 mass%, and a tensile strength is 660 MPa to 900 MPa is welded with the flux-cored wire for gas-shielded arc welding according to any one of (1) to (8), and with any one of a pure Ar gas, a mixed gas of Ar and 1.5 volume% or less of O₂ or CO₂, a pure He gas, and a mixed gas of He and 1.5 volume% or less of O₂ or CO₂ as a shielding gas.

[Effects of the Invention]

[0025] According to each of the aspects of the present invention, gas-shielded arc welding capable of significantly reducing welding material costs by reducing the amount of Ni to the flux-cored wire used for welding Ni-based steel for low temperature use containing about 5.5% to 9.5% of Ni to the same level as Ni-based steel for low temperature use and achieving excellent welding efficiency can be applied, and further, a weld metal having excellent low temperature toughness at - 196°C can be obtained by reducing the alloy composition of the flux to fill the inside of the wire and the amount of oxygen in the weld metal. Further, it is possible to provide a flux-cored wire in which preheating for preventing cold cracking is not required or preheating can be significantly reduced, a method for welding steel for very low temperature use using the same, and a method for manufacturing a welding joint.

[Brief Description of the Drawing]

[0026] 

FIG. 1 is a view showing a relationship between SM and Charpy absorbed energy at -196°C (when the entire outer steel sheath is made of mild steel).

FIG. 2 is a view showing a relationship between SM and Charpy absorbed energy at -196°C (when the entire outer steel sheath is made of Ni-containing steel).

FIG 3 is a view showing a relationship between an amount of CaO and an amount of diffusible hydrogen (when the entire outer steel sheath is made of mild steel).

FIG. 4 is a view showing a relationship between an amount of CaO and an amount of diffusible hydrogen (when the entire outer steel sheath is made of Ni-containing steel).

FIG 5 is a cross-sectional view of a cut wire.

FIG 6 is a view showing a relationship between an amount of oxygen in a weld metal and Charpy absorbed energy at -196°C (when the entire outer steel sheath is made of mild steel).

FIG. 7 is a view showing a relationship between an amount of oxygen in a weld metal and Charpy absorbed energy at -196°C (when the entire outer steel sheath is made of Ni-containing steel).

FIG. 8 is a view showing a position where a test piece is collected in an example (JIS Z 3111-2005).

[Embodiments of the Invention]

[0027] A weld metal of Ni-based steel for low temperature use requires low temperature toughness at -196°C and an amount of oxygen in the weld metal needs to be reduced to secure absorbed energy at -196°C.

[0028] As a method for reducing the amount of oxygen in the weld metal, the use of gas-shielded arc welding using an inert gas may be considered. However, since arcs are unstable and a sound weld metal without weld defects is hardly obtained, the gas-shielded arc welding has not been used.

[0029] Thus, only a Ni-based alloy welding material or means for using a method in which welding efficiency is very low such as TIG welding has been used. The former has a problem of very high welding material costs, and the latter has a problem of a very low welding efficiency. Thus, a welding material in which welding material costs are low and welding efficiency is high has not been realized.

[0030] The present inventors have performed welding of Ni-based steel for low temperature use using wires, which are a flux-cored wire in which the amount of Ni is reduced at the same level as Ni-based steel for low temperature use and which are prepared with different amounts of CaF₂ and a metal oxide at various ratios and further with different amounts of C, Si, Mn, and other alloy elements at various ratios, by gas-shielded arc welding using an inert gas.

[0031]  As a result, (i) in a specific range of the amounts of CaF₂ and the metal oxide, arcs are stable even in the gas-shielded arc welding using an inert gas and a sound weld metal can be obtained. (ii) Not only can an inert gas be used but also the use of an outer steel sheath including Ni enables significant reduction in the amount of oxygen in the weld metal. (iii) In a specific range of the amounts of C, Si, Mn, and other alloy elements, excellent low temperature toughness at -196°C can be obtained. (iv) In a specific range of the amount of CaF₂, the amount of diffusible hydrogen in the weld metal can be significantly reduced. (v) Preheating required for preventing cold cracking which is a problem arising when the amount of Ni is reduced to the same level as Ni-based steel for low temperature use is not required or the preheating can be significantly reduced. The above-described points (i) to (v) have been found.

[0032] The present invention has been made based on the results of the above investigations and reasons for limiting characterized technical requirements and preferable embodiments with respect to a flux-cored wire according to an embodiment will be sequentially described below.

[0033] First, the reasons why the amounts of an alloy composition, a metal deoxidizing composition, and each composition contained in an outer steel sheath constituting the flux-cored wire of the embodiment and a flux are limited will be described.

[0034] In the following description, unless otherwise specified, "%" means "mass% and an amount of each composition means a composition amount which is total mass% of each composition in the outer steel sheath and the flux with respect to a total mass of the wire.

(C: 0.003% to 0.040%)

[0035] C is an element for increasing strength and 0.003% or more of C needs to be contained to secure the strength. In order to increase the strength, the lower limit of the amount of C may be 0.005%, 0.008%, 0.010%, or 0.013%. On the other hand, a weld metal containing 6% to 16% of Ni has a hard martensite structure. An influence of C affecting the hardness of martensite is very significant and when the amount of C is more than 0.040%, the weld metal becomes very hard and the toughness significantly decreases. Thus, the upper limit of the amount of C is 0.040%. In order to stably secure the toughness, the upper limit of the amount of C may be 0.035% or 0.030%.

(Si: 0.05% to 0.40%)

[0036] Si is an element required for increasing the cleanliness of the weld metal and preventing the generation of weld defects such as a blowhole. In order to obtain these effects, 0.05% or more of Si needs to be contained. In order to prevent the generation of the weld defects, the lower limit of the amount of Si may be 0.09% or 0.14%. On the other hand, Si is easily micro-segregated in the weld metal containing 6% to 16% of Ni. When the amount of Si is more than 0.40%, remarkable embrittlement is caused in the segregated portion, and thus, 0.40% is the upper limit. In addition, the upper limit of the amount of Si may be 0.35% or 0.30% to stably secure the toughness of the weld metal.

(Mn: 0.2% to 0.8%)

[0037] Mn is an element required for increasing the cleanliness of the weld metal and detoxifying S by forming MnS to improve toughness. In order to obtain these effects, 0.2% or more of Mn needs to be contained. In order to further improve the toughness, the lower limit of the amount of Mn may be 0.3%, 0.35%, or 0.4%. On the other hand, Mn is easily micro-segregated in the weld metal containing 6% to 16% of Ni. When the amount of Mn is more than 0.8%, remarkable embrittlement is caused in the segregated portion, and thus, 0.8%, is set as an upper limit. In addition, the upper limit of the amount of Mn may be 0.7%, 0.6%, or 0.5% to stably secure the toughness of the weld metal.

(P: 0.02% or less)

[0038] P is an impurity element and deteriorates toughness. Thus, the amount of P is necessarily decreased as much as possible. However, as a range in which the adverse effect on toughness is allowable, the amount of P is limited to 0.02% or less. In order to further improve the toughness, the upper limit of the amount of P may be 0.015%, 0.01 %, 0.008%, or 0.006%. The lower limit of the amount of P does not need to be limited and the lower limit of the amount of P is 0%.

(S: 0.01% or less)

[0039] S is an impurity element and deteriorates toughness. Thus, it is preferable that the amount of S be decreased as much as possible. As a range in which the adverse effect on toughness is allowable, the amount of S is limited to 0.01% or less. In order to further improve the toughness, the upper limit of the amount of S may be 0.008%, 0.006%, 0.004%, or 0.003%. The lower limit of the amount of S does not need to be limited and the lower limit of the amount of S is 0%.

(Al: 0.003% to 0.050%)

[0040] Al is a deoxidizing element and is effective in increasing cleanliness similar to Si and Mn. In order to exert the effect, 0.003% or more of Al is contained. On the other hand, when the amount of Al is more than 0.050%, nitrides and oxides are formed and the toughness of the weld metal is deteriorated. Therefore, 0.050% is set as an upper limit. In addition, the lower limit of the amount of Al may be 0.005%, 0.007%, 0.009%, or 0.011% to obtain a sufficient effect of improving the toughness of the weld metal, and the upper limit of the amount of Al may be 0.040%, 0.035%, 0.030%, or 0.025% to suppress the formation of oxides.

(Ni: 6.0% to 16.0%)

[0041] Ni is a unique element capable of improving toughness by solid solution toughening (an action of increasing toughness by solid solution) irrespective of a structure and composition and is an element particularly required for securing low temperature toughness at -196°C. In order to obtain this effect, it is necessary to set the amount of Ni to 6.0% or more. On the other hand, when the amount of Ni is more than 16.0%, the effect thereof is saturated and further welding material costs increase excessively, and thus, the aforementioned amount of Ni is not preferable. The upper limit of the amount of Ni may be limited to 14% or 12%. In order to stably secure the low temperature toughness, the lower limit of the amount of Ni may be 6.5%, 7.0%, or 7.5%, or 8.0%.

[0042] In addition, Ni may be added to the weld metal mainly from the outer steel sheath. A metal power added as a flux has a thin oxide layer and the layer is an oxygen source of the weld metal. When the outer steel sheath of mild steel is used, it is necessary to add a large amount of metal powder as a flux for the addition of Ni, and oxygen in the weld metal increases due to the metal powder. In order to suppress an increase of oxygen and improve the toughness, Ni may be contained mainly in the outer steel sheath. Therefore, the amount of Ni contained in the outer steel sheath may be 6.0% or more, by mass%, with respect to the mass of the outer steel sheath. The upper limit of the amount of Ni in the outer steel sheath does not need to be particularly limited. However, the upper limit of the amount of Ni in the outer steel sheath may be 18% so that the amount of Ni is 16% or less with respect to the total mass of the wire. The upper limit of the amount of Ni in the outer steel sheath may be 17% or 16% as required.

[0043] Since a melting point of a Ni alloy is lower than a melting point of mild steel, the difference between melting points of the outer steel sheath and the flux increases when a Ni alloy is used in the outer steel sheath. Accordingly, the flux is stabilized as a core and thus droplet transfer is more stabilized. For relative comparison, the outer steel sheath made of a Ni alloy has a small amount of oxygen in the weld metal and high low temperature toughness.

[0044] In the present invention, for the following purposes, one or more of each element of Cu, Cr, Mo, V, Ti, Nb, B, Mg, and REM can be contained as an optional element.

(Cu: 0% to 0.5%)

[0045] Cu has an effect of increasing the strength of the weld metal when Cu is included in plating of the outer steel sheath of the wire or flux of the wire as a single body or an alloy. Although the lower limit of the amount of Cu is 0%, Cu may be contained. If the amount of Cu is more than 0.5%, the toughness is deteriorated. Thus, the amount of Cu is 0.5% or less. In order to improve the toughness, the upper limit of the amount of Cu may be 0.3%, 0.2%, or 0.1%. Here, the amount of Cu includes a part contained in the outer steel sheath and the flux as well as a part of Cu plating if the Cu plating is plated on the surface of the wire. In order to obtain the effect by containing, the lower limit of the amount of Cu may be 0.01%.

(Cr: 0% to 0.5%)

[0046] Cr is an effective element for increasing the strength of the weld metal. The lower limit of the amount of Cr is 0%. If Cr is contained, when the amount of Cr is more than 0.5%, the toughness is deteriorated. Thus, the amount of Cr is 0.5% or less. In order to improve the toughness, the upper limit of the amount of Cr may be 0.3%, 0.2%, or 0.1%. In order to obtain the effect by containing, the lower limit of the amount of Cr may be 0.01%.

(Mo: 0% to 0.5%)

[0047] Mo is an effective element in increasing the strength of the weld metal by precipitation strengthening. The lower limit of the amount of Mo is 0%. If the amount of Mo when being added is more than 0.5%, the toughness is deteriorated. Thus, the amount of Mo is 0.5% or less. In order to improve the toughness, the upper limit of the amount of Mo may be 0.3%, 0.2%, or 0.1%. In order to obtain the effect by containing, the lower limit of the amount of Mo may be 0.01%.

(V: 0% to 0.2%)

[0048] V is an effective element in increasing the strength of the weld metal by precipitation strengthening. The lower limit of the amount of V is 0%. If the amount of V when being added is more than 0.2%, the toughness is deteriorated. Thus, the amount of V when being contained is 0.2% or less. In order to improve the toughness, the upper limit of the amount of V maybe 0.15%, 0.1%, or 0.05%. In order to obtain the effect by containing, the lower limit of the amount of V may be 0.01%.

(Ti: 0% to 0.1%)

[0049] Ti is effective in alleviating the adverse effect of solid-soluted N on toughness by fixing the solid-soluted N. Further, Ti is effectively used as a deoxidizing element and has an effect of reducing the amount of O in the weld metal. The lower limit of the amount of Ti is 0%. If the amount of Ti when being added is more than 0.1% and the amount of Ti is excessive, carbides are formed and the toughness is deteriorated. Thus, the amount of Ti when being contained is 0.1% or less. In order to improve the toughness, the upper limit of the amount of Ti may be 0.06%, 0.04%, or 0.02%. In order to obtain the effect by containing, the lower limit of the amount of Ti may be 0.005%.

(Nb: 0% to 0.1%)

[0050] Nb is effective in increasing the strength of the weld metal by precipitation strengthening. The lower limit of the amount of Nb is 0%. If the amount of Nb when being added is more than 0.1%, coarse precipitates are formed in the weld metal and the toughness is deteriorated. Thus, the amount of Nb when being contained is 0.1 % or less. In order to improve the toughness, the upper limit of the amount of Ti may be 0.06%, 0.04%, or 0.02%. In order to obtain the effect by containing, the lower limit of the amount of Nb may be 0.002%.

(B: 0% to 0.01%)

[0051] When an appropriate amount of B is contained in the weld metal, B has an effect of alleviating the adverse effect of the solid-soluted N on toughness by being combined with solid-soluted N to form BN. The lower limit of the amount of B is 0%. If the amount of B when being added is more than 0.01%, the amount of B is excessive in the weld metal and the excess B forms coarse BN and B-compounds such as Fe₂₃(C,B)₆, which deteriorates toughness. Thus, the amount of B when being contained is 0.01 % or less. In order to improve the toughness, the upper limit of the amount of B may be 0.006%, 0.004%, or 0.002%. In order to obtain the effect by containing, the lower limit of the amount of B may be 0.0003%.

(Mg: 0% to 0.6%)

[0052] Mg is a strongly deoxidizing element and has an effect of improving toughness by reducing the amount of oxygen in the weld metal. The lower limit of the amount of Mg is 0%. If the amount of Mg when being added is more than 0.6%, the amount of spatter increases and welding efficiency is deteriorated. Thus, the amount of Mg when being contained is 0.6% or less. In order to improve the welding efficiency, the upper limit of the amount of Mg may be 0.4%, 0.2% or 0.1 %. In order to obtain the effect by containing, the lower limit of the amount of Mg may be 0.05%.

(REM: 0% to 0.0500%)

[0053] When an excessive amount of REM is contained, spattering is violent and welding efficiency is deteriorated. Therefore, the lower limit of the amount of REM is 0%. An effective amount of REM in which the amount of spatter is reduced and arcs are stable when being added is 0.0500% or less. In addition, in order to contribute to spattering reduction and stable arcs, the upper limit of the amount of REM maybe 0.0300%, 0.0200%, 0.0100%, 0.0050%, or 0.0010%.

[0054] In the flux-cored wire of the embodiment, each element is contained as an alloy composition or a metal deoxidizing composition as described above. However, in order to secure the low temperature toughness at -196°C, it is necessary to set a total amount SM of Si and Mn shown in the following Table 1 to be 0.3% to 1.0%.

[0055] In the expression, elements noted in brackets express amounts (mass%) of the elements, respectively.

[0056] The flux-cored wire of the embodiment enables stable welding during the gas-shielded arc welding in which pure Ar or pure He is used as a shielding gas or a mixed gas in which a ratio of O₂ or CO₂ in Ar or He is less than 2 volume% is used as a shielding gas. However, a thin oxide layer is present around the metal powder filled in the flux-cored wire and oxygen is introduced into the weld metal although the amount of oxygen is small.

[0057] At this time, when the amount of Si and Mn which improves the cleanliness of the weld metal is not sufficient, weld defects such as a blowhole is generated in the weld metal due to oxygen from the wire. In order to prevent such weld defects, it is necessary to contain Si and Mn such that the SM is 0.3% or more. On the other hand, in the weld metal containing 6% to 16% of Ni, Si and Mn are easily micro-segregated and remarkable embrittlement is caused in the segregated portion. When the SM is 1.0% or less, embrittlement is allowable in the segregated portion and thus 1.0% is set as an upper limit. In order to more reliably prevent the weld defects, the lower limit of the SM may be 0.35% or 0.4%.

[0058] The experiments by which such findings are obtained are shown in FIGS. 1 and 2. The entire outer steel sheath of the flux-cored wire used in FIG. 1 is made of mild steel, and the entire outer steel sheath of the flux-cored wire used in FIG. 2 is made of Ni-containing steel. FIGS. 1 and 2 show relationships between Charpy absorbed energy at -196°C and SM of a wire obtained using a test piece that is prepared from a weld metal obtained by preparing flux-cored wires which satisfy the requirements of the present invention except that the SM value is different, and performing welding using the wires in the same manner as in examples which will be described later.

[0059] As seen from FIG. 1, in the wire in which Si and Mn are added such that the SM is 0.3 to 1.0, the Charpy absorbed energy at -196°C was 50J or more. As seen from FIG. 2, in the wire in which Si and Mn are added such that the SM is 0.3 to 1.0, the Charpy absorbed energy at -196°C was 69J or more. When the entire outer steel sheath is made of mild steel, in order to stably secure an absorbed energy of 50J or more, the upper limit of the SM may be 0.9%, 0.8%, 0.75%, or 0.70%. When the entire outer steel sheath is made of Ni-containing steel, in order to stably secure an absorbed energy of 69J or more, the upper limit of the SM may be 0.9%, 0.8%, 0.75%, or 0.70%.

(Carbon equivalent Ceq: 0.250% to 0.525%)

[0060] Further, in the flux-cored wire of the embodiment, the amounts of C, Si, Mn, Ni, Cr, Mo, and V are adjusted so that a carbon equivalent Ceq, expressed by the following expression 2 and defined by the Japan Welding Engineering Society (WES), is 0.250% to 0.525%.

[0061] In the expression, elements noted in brackets express amounts of the elements, by mass%, respectively.

[0062] Although the tensile strength of the weld metal is increased as the Ceq value increases, the toughness is deteriorated and the weld cracking parameter is increased as the Ceq value increases. Thus, a countermeasure for preventing cold cracking is required. When the Ceq value is less than 0.250%, a target strength (tensile strength) of the weld metal of 660 MPa or more cannot be satisfied. On the other hand, when the Ceq value is more than 0.525%, the tensile strength of the weld metal becomes excessive and the toughness of the weld metal is deteriorated. Therefore, the range of the Ceq is from 0.250% to 0.525%. In order to stably secure the strength, the lower limit of the Ceq value may be 0.290%, 0.330%, or 0.370%. In order to improve the toughness, the upper limit of the Ceq may be 0.490%, 0.460%, or 0.430%.

[0063] Here, the amount of the elements contained in the wire as the above alloy composition and metal deoxidizing composition does not include the amount of the elements when the elements are contained as a metal fluoride, a metal oxide, and a metal carbonate.

[0064] In addition, these elements are not necessarily pure substances (impurities may be contained) and there is no problem even when the elements may be contained in the form of alloys such as Fe-Mn and Cu-Ni. Further, even when these elements are contained in the outer steel sheath, or as the flux, the same effect is exerted. Thus, the elements may be contained in any of the outer steel sheath and the flux.

[0065] Subsequently, a flux composition which is inserted into the outer steel sheath of the wire will be described.

(Total amount α of metal fluoride including CaF₂ as main composition: 2.0% to 7.0%)

[0066] In the related art, in the gas-shielded arc welding using an inert gas, a thermal pinch force and electromagnetic pinch force generated during welding are small, and thus, a droplet formed at the tip end of the wire does not drop from the wire and the molten portion extends like a liquid column. The molten portion is swayed like a whip by affection of a plasma airflow and magnetic blow. Then, the state of arcs becomes very unstable and welding is not possible.

[0067] In the embodiment, when a metal fluoride including CaF₂ as a main composition was used as a flux composition for the flux-cored wire, stable welding was possible even in gas-shielded arc welding using an inert gas. The outer steel sheath melts under the arcs. However, since the metal fluoride has a low electric conductivity, the flux inside the wire does not melt completely and remains as a core, and the core of the flux is introduced straightly into a molten pool without swaying like a whip. At this time, the molten outer steel sheath is moved to the molten pool along the core of the flux, and thus, stable welding is possible.

[0068] In order to make stable welding possible even in the gas-shielded arc welding using an inert gas, it is necessary to contain the metal fluoride including CaF₂ such that when a total amount thereof is defined as α, the α is 2.0% or more and a ratio ([CaF₂]/α) of the amount of [CaF₂] with respect to the α is 0.90% or more. The larger the amount of CaF₂ is, the more preferable it is. The lower limit of the ratio may be 0.93, 0.96, 0.98, or 0.99. There is no problem when the ratio is 1.0 and only CaF₂ is used.

[0069] When the total amount α of the metal fluoride is less than 2.0%, the core of the flux remains insufficient during the welding and thus welding is unstable. On the other hand, when the total amount α of the metal fluoride is more than 7.0%, excessive welding fume is generated and welding is unstable. Thus, the above total amount is not preferable.

[0070] In order to secure more stable weldability even in the gas-shielded arc welding using an inert gas, the lower limit of the total amount α of the metal fluoride may be 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, or 3.4%, and the upper limit of the total amount α of the metal fluoride may be 6.5%, 6.0%, 5.5%, or 5.0%.

[0071] As the metal fluoride, in addition to CaF₂, one or more of BaF₂, SrF₂, MgF₂, and LiF can be contained as required. However, from the viewpoint of securing arc stability and suppressing spattering, a ratio of the amount of CaF₂ with respect to a total amount of CaF₂, BaF₂, SrF₂, MgF₂, and LiF has to be 0.90 or more. When the ratio is less than 0.90, the arc stability is deteriorated. The higher the ratio of CaF₂ is, the more preferable it is. The ratio may be 0.93% or more, 0.96% or more, 0.98% or more, or 0.99% or more. There is no problem when the ratio of CaF₂ is 100%.

[0072]  In addition to the above-described actions, the metal fluoride also has an action of reducing the amount of diffusible hydrogen in the weld metal.

[0073] The weld metal containing 6% to 16% of Ni has a very hard martensite structure. Therefore, preheating is required for preventing cold cracking. However, since the metal fluoride can reduce the amount of diffusible hydrogen in the weld metal, the metal fluoride makes it possible that welding is performed with omitting or simplifying preheating required to prevent cold cracking.

[0074] The fact that the metal fluoride has an action of reducing the amount of diffusible hydrogen is known by a covered arc electrode. However, an example in which a diffusible hydrogen reduction in the flux-cored wire is investigated in detail does not exist. In the embodiment, the most suitable form for reducing the diffusible hydrogen has been found in consideration of other flux compositions, mechanical properties of the weld metal, welding workability, or the like.

[0075] The reason why the metal fluoride reduces the diffusible hydrogen is that the metal fluoride is decomposed by welding arcs, the generated fluorine is bonded with hydrogen and dispersed in the air as a HF gas, or hydrogen is fixed in the weld metal as a HF gas without any change.

(Ti oxide: 0% to 0.4%)

[0076] In order to improve low temperature toughness by reducing the amount of oxygen in the weld metal, it is preferable to reduce the amount of TiO₂, included as Ti oxide, as much as possible. Therefore, the lower limit of TiO₂ is 0%. On the other hand, in order to obtain good bead formability, slag peelability, and arc stability, it is preferable to add TiO₂. Therefore, the lower limit of the amount of TiO₂ may be 0.05%, 0.1%, 0.13%, 0.16%, or 0.19%. When the amount of TiO₂ is more than 0.4%, oxygen included in TiO₂ is introduced into the molten pool and thus the amount of oxygen in the weld metal increases and the absorbed energy at ductile fracture decreases. Thus, the upper limit is 0.4%. The upper limit of the amount of TiO₂ may be 0.35%, 0.31 %, 0.27%, or 0.24% as required. When the low temperature toughness is emphasized, the upper limit of the amount of TiO₂ maybe 0.2%, 0.15%, 0.12%, or 0.09%.

(Si oxide: 0.2% to 0.5%)

[0077] SiC₂, included as Si oxide, is necessary to arrange the form of slag and make slag peeling easy after welding. In order to exert the effect, the amount of SiO₂ is necessarily 0.2% or more. The lower limit of the amount of SiO₂ may be 0.23%, 0.26%, or 0.29%. However, when the amount of SiO₂ contained is more than 0.5%, oxygen included in the SiO₂ is introduced into the molten pool and the amount of oxygen in the weld metal increases and the absorbed energy at ductile fracture decreases. Therefore, 0.5% is set as an upper limit. The upper limit of the amount of SiO₂ may be 0.45%, 0.39%, 0.37%, or 0.34%.

(Total amount of metal oxide: 0.2% to 0.9%)

[0078] In the flux-cored wire of the embodiment, as a slag forming agent one or more metal oxides such as a Ti oxide, a Si oxide, a Mg oxide, an Al oxide, a Zr oxide, and a Ca oxide, for example, TiO₂, SiO₂, MgO, Al₂O₃, ZrO₂, and CaO, are included. These metal oxides are included to maintain a good weld bead shape. In order to obtain the appropriate effect of the metal oxides, when a total amount of the metal oxides is defined as β, it is necessary to set the lower limit of the β to be 0.2%. However, when the total amount P of the metal oxides is more than 0.9%, the amount of oxygen in the weld metal increases and the toughness is deteriorated. Thus, the above total amount is not preferable.

[0079] The total amount of these metal oxides includes, in addition to the total amount of TiO₂, SiO₂, MgO, Al₂O₃, ZrO₂, and CaO, an amount of a metal oxide included in a binder or the like which is used in flux granulation. In order to reliably obtain the effect of these metal oxides, the lower limit of the total content of the metal oxides may be 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Further, in order to suppress deterioration in the toughness of the weld metal due to the containing of the metal oxides as much as possible, the upper limit of the total amount β of the metal oxides may be 0.8%, 0.7%, or 0.6%.

(Arc stabilizer: 0% to 0.50%)

[0080] Additionally, an arc stabilizer may be further contained in the flux. As the arc stabilizer, there are oxides or fluorides of Na or K (for example, Na₂O, NaF, K₂O, KF, K₂SiF₆, and K₂ZrF₆) or the like, and the total amount thereof is 0% to 0.50%. Since the arc stabilizer may not be necessarily contained, the lower limit of the total amount of oxides or fluorides of Na or K is 0%. In addition, since arcs become stronger and the amount of spatter increases, the upper limit is 0.50%. The oxides and fluorides as the arc stabilizer described as an example herein may not include the above-described metal oxides functioning as the slag forming agent and metal fluorides used to reduce the amount of diffusible hydrogen. When the amount of the oxides and fluorides of Na and K is large, arcs become stronger and the amount of spatter increases. Thus, the total amount of the compounds may be limited to 0.40% or less, 0.30% or less, or less than 0.20%, 0.10% or less, as required.

[0081] In addition to the amount of each of the above-described metal oxides and metal fluorides, it is necessary that a ratio (α/β) of the total amount α of the metal fluoride with respect to the total amount β of the metal oxide expressed by mass% satisfy 3.0 or more and 15.0 or less.

[0082] When the value of α/β is less than 3.0, the amount of oxygen in the weld metal increases, which causes a decrease in the absorbed energy. When the value of α/β is more than 15.0, arcs easily become unstable in the gas-shielded arc welding using an inert gas. As required, the lower limit of α/β may be 3.5 or 4.0, and the upper limit thereof may be 14.0,13.0, or 12.0. In addition, it is important to control the value of the ratio α/β to obtain the effect of reducing the amount of diffusible hydrogen, and the effect of reducing the amount of diffusible hydrogen can be obtained as long as the value is within the range of the embodiment.

(Ca oxide: less than 0.20%)

[0083] In the embodiment, the amount of CaO, included as Ca oxide, contained in the flux is limited. CaO is contained as a raw material for the flux in some cases. Even in this case, the amount of CaO is limited to less than 0.20%, by mass%, with respect to the total mass of the flux-cored wire. When the amount of CaO is limited to less than 0.20%, the effects of the present invention can be obtained. That is, the raw material for the flux is preferably selected such that the upper limit of the amount of CaO is less than 0.20%. As required, the upper limit of the amount of CaO may be limited to less than 0.18%, less than 0.15%, less than 0.12%, less than 0.10%, less than 0.08%, less than 0.06%, or less than 0.04%. The lower limit of the amount of CaO may be 0%. Due to the selection of the raw material for the flux, the lower limit of the amount of CaO may be 0.01% or 0.005%.

[0084] Since CaO is changed to CaOH which is a compound including hydrogen by being exposed to the air, the amount of diffusible hydrogen in the weld metal is increased. The experiments from which such finds are obtained are shown in FIGS. 3 and 4.

[0085] FIG. 3 shows a relationship between the amount of CaO in flux-cored wires and the amount of diffusible hydrogen obtained by preparing flux-cored wires which satisfy the requirements of the present invention except that the value of CaO is different and which have the entire outer steel sheath being made of mild steel, performing welding using the wires, and measuring an amount of diffusible hydrogen in obtained weld metals in the same manner as in examples which will be described later.

[0086] FIG. 4 shows a relationship between the amount of CaO in flux-cored wires and the amount of diffusible hydrogen obtained by preparing flux-cored wires which satisfy the requirements of the present invention except that the value of CaO is different and which have the entire outer steel sheath being made of Ni-containing steel, performing welding using the wires, and measuring an amount of diffusible hydrogen in obtained weld metals in the same manner as in examples which will be described later.

[0087] From FIGS. 3 and 4, as the amount of CaO increases, the amount of diffusible hydrogen in the weld metal increases. Until the amount of CaO reaches 0.20%, an amount of diffusible hydrogen of 1.5 ml/100g or less can be obtained. The amount of CaO is less than 0.20%, since the effect of reduction of preheating can be obtained when the amount of diffusible hydrogen is 1.5 ml/100g or less. That is, the raw material for the flux is selected such that the ranges are satisfied.

(Metal carbonate: less than 0.60%)

[0088] For the purpose of an action of stabilizing arcs and increasing arc convergence, the flux-cored wire of the embodiment may contain one or more metal carbonates of CaCO₃, BaCO₃, SrCO₃, MgCO₃, and Li₂CO₃. When a total amount of metal carbonates is 0.60% or more, arc convergence becomes excessively stronger and the amount of spatter generated increases. Therefore, the total amount of the metal carbonates is less than 0.60%. As required, the total amount may be 0.40% or less, 0.20% or less, 0.10% or less, or 0.07% or less. These metal carbonates are not necessarily contained in the wire and the lower limit thereof is 0%.

(Iron powder: less than 5%)

[0089] An iron powder is contained in the flux-cored wire to adjust a flux filling rate in the flux-cored wire or improve deposition efficiency in some cases as required. However, since the surface layer of the iron powder is oxidized, the amount of oxygen in the weld metal may increase and the toughness may be deteriorated when the flux contains excessive ion powder. Accordingly, the iron powder may not be contained. That is, the lower limit thereof is 0%. When the iron powder is contained to adjust the filling rate, the upper limit of the amount of the iron powder is less than 5% to secure the toughness of the weld metal.

[0090]  The reason why the chemical composition of the flux-cored wire of the embodiment is limited has been described above. Other alloy chemical compositions as a remainder are iron and impurities. The iron composition includes iron of the outer steel sheath, an iron powder included in the flux, and iron in alloy compositions. In addition, a remainder including iron as a main composition may contain impurities entering during the manufacturing process in a range not inhibiting the characteristics of the present invention.

(Filling rate: 5.0% to 30.0%)

[0091] Since a hollow space inside the outer steel sheath is filled with the flux, there is an upper limit in a filling rate. The upper limit of the filling rate varies depending on the thickness of the outer steel sheath. However, a preferable value of upper limit of the filling rate is 30.0% to stably add the flux. The upper limit of the filling rate may be 25.0%, 20.0%, or 15.0%. In addition, regarding the lower limit of the filling rate, when the filling rate is too low, the flux filling the inside of the outer steel sheath does not have a frictional force with the outer steel sheath and can be moved and thus, there is a concern of a dense flux. Therefore, the lower limit of the filling rate is preferably 5%.

[0092] Subsequently, the shape of the flux-cored wire will be described.

[0093] The flux-cored wire can be roughly divided into a seamless wire in which a slit-shaped gap does not exist in the outer steel sheath, and a wire with a seam in which a slit-shaped gap exists in the outer steel sheath.

[0094] In the present invention, any cross-sectional structure can be employed. However, in order to prevent cold cracking of the weld metal, it is preferable to form a (seamless) wire in which a slit-shaped gap does not exist.

[0095] In addition, in order to improve the feedability of the wire during the welding, a lubricant can be applied onto the surface of the wire. As the lubricant for a weld wire, various kinds of lubricants can be used. However, in order to prevent the cold cracking of the weld metal, a perfluoropolyether oil (PFPE oil) is preferably used.

[0096] Hydrogen penetrated into the weld portion during the welding diffuses into the weld metal and steel, is accumulated in a stress concentration portion, and causes cold cracking. Examples of the hydrogen source include moisture that the welding material holds, moisture entering from the air, and rust or scales adhering onto the surface of the steel. In the welding in which the cleanliness of the weld portion and conditions for gas-shielding are sufficiently managed, hydrogen contained mainly as moisture in the wire is a major cause for diffusible hydrogen present in the weld joint.

[0097] Therefore, it is preferable to suppress penetration of hydrogen in the air from the outer steel sheath to the flux in a period from the manufacturing of the wire to the use of the wire by using a (seamless) tube in which a slit-shaped gap does not exist for the outer steel sheath.

[0098] When a tube (with a seam) in which a slit-shaped gap exists is used for the outer steel sheath, the moisture in the air easily penetrates into the flux from the slit-shaped gap (seam portion) on the outer steel sheath and in this state, the penetration of the hydrogen source such as moisture cannot be prevented. Accordingly, when the period from the manufacturing of the wire to the use of the wire is long, it is preferable that the entire wire be vacuum-packed or stored in a container in which the wire can be stored in a dried state.

[0099] In the present invention, the tensile strength of the weld metal has the same level as that of high strength steel having a tensile strength of 660 MPa to 900 MPa. The tensile strength of the weld metal can be measured in such a manner that a tensile test defined in Japanese Industrial Standards JIS Z 3111-2005 is performed on the weld metal of the weld joint prepared using the flux-cored wire. Further, a good correlation between hardness and tensile strength has been known. The tensile strength of the weld metal may be obtained by measuring the hardness of the weld metal of the weld joint and converting the hardness into the tensile strength using the correlation. The lower limit of the tensile strength of the weld metal may be limited to 685 MPa and the upper limit thereof may be limited to 830 MPa as required.

[0100] The flux-cored wire used in the embodiment can be manufactured in the same manufacturing steps as in a method for manufacturing a typical flux-cored wire.

[0101] That is, first, a steel strip which becomes the outer steel sheath and a flux in which a metal fluoride, an alloy composition, a metal oxide, a metal carbonate, and an arc stabilizer are blended so as to have a predetermined amount are prepared. While being fed in the longitudinal direction, a steel strip is formed into an open tube (U-shaped tube) by a forming roll to be set as an outer steel sheath, the flux is supplied from an opening portion of the open tube in the middle of the forming, and edge surfaces facing each other at the opening portion is subjected to butt seam welding by electric sewing welding, laser beam welding, or TIG welding. The tube having no gap obtained by the welding is wire-drawn and is subjected to annealing in the middle of the wire-drawing or after the completion of the wire-drawing so as to obtain a (seamless) wire having no slit-shaped gap and a predetermined wire diameter and including the flux to fill the inside of the outer steel sheath. In addition, a wire (with the seam) in which a slit-shaped gap exists can be obtained by supplying the flux from the opening portion of the open tube, forming a tube having a gap on which seam welding is not performed, and wire-drawing the tube.

[0102] Here, the shape of the seamless wire, particularly, the cross sectional structure thereof will be described using FIGS. 5A to 5C. FIGS. 5A to 5C are views showing cross sections of the wires.

[0103] A cross section of a wire which is prepared by butt seam welding and has no slit-shaped gap can be seen as in FIG. 5A. When this cross section is polished and etched, a welding trace is observed. However, when the wire is not etched, the welding trace is not observed. Therefore, the wire is called a seamless wire in some cases. In "1000 numbers of Q and A of Bonding and Joining Technology", compiled by the editorial committee of 1000 numbers of Q and A of Bonding and Joining Technology, and published by Industrial Technology Center Incorporated, p.564, the wire is described as a seamless type. Further, even when a gap exists as shown in FIGS. 5B and 5C, the wire is butted and brazed, or caulked and brazed and then a wire in which a slit-shaped gap does not exist can be obtained. In FIGS. 5B and 5C, the wire on which brazing is not performed is a wire in which a slit-shaped gap exists as shown in the drawings.

[0104] The flux-cored wire of the embodiment may be used for performing gas-shielded arc welding on Ni-based steel for low temperature use including 5.5% to 5.9% of Ni. Steel having an amount of Ni of 5.5% to 5.9%, a thickness of 6 mm or more and 100 mm, a tensile strength of 660 MPa to 900 MPa, and a Charpy absorbed energy at -196°C of 41J or more or 50J or more is used for an LNG storage tank. When the steel is subjected to welding, the flux-cored wire of the embodiment can be used to manufacture a weld joint. In this case, a person having substantial experience in welding for LNG tank may manufacture weld joint having good characteristics only with taking care of selection of shielding gas.

[0105] Pure Ar gas or Pure He gas may be used for the shielding gas used to weld. In addition, even if the pure Ar gas or the pure He gas are mixed with 1.5 volume% or less of O₂ or 1.5 volume% or less of CO₂, the effect according to the present invention can be obtained.

[0106] The experiment results obtained from such findings are shown in FIGS. 6 and 7. FIGS. 6 and 7 show results obtained by welding 9% Ni steels with a pure Ar gas, a mixed gas of Ar with O₂ at various concentrations, a mixed gas of Ar with CO₂ at various concentrations, a pure He gas, a mixed gas of He with O₂ at various concentrations, or a mixed gas of He with CO₂ at various concentrations as a shielding gas and with the flux-cored wire having the chemical composition of the embodiment and then measuring the amount of oxygen and the Charpy absorbed energy at -196°C of the weld metals. Here, the entire outer steel sheaths of the flux-cored wires used in FIG. 6 are made of mild steel, and the entire outer steel sheaths of the flux-cored wires used in FIG. 7 are made of Ni-containing carbon steel. The amounts of Ni in the Ni-containing steels are 6% to 18%.

[0107] In FIG. 6, when a mixed gas in which O₂ or CO₂ was contained in the pure Ar gas or the pure He gas within a range of 1.5 volume% or less was used, the amounts of oxygen in all of the weld metals were 160 ppm or less. Further, when the amounts of oxygen in the weld metals were 160 ppm or less, Charpy absorbed energy thereof at - 196°C is 50J or more.

[0108] In FIG 7, when a mixed gas in which O₂ or CO₂ was contained in the pure Ar gas or the pure He gas within a range of 1.5 volume% or less was used, the amounts of oxygen in all of the weld metals were 80 ppm or less. In addition, when the amounts of oxygen in the weld metals were 80 ppm or less, Charpy absorbed energy thereof at - 196°C is 69J or more.

[0109] As described above, the shielding gas used to weld is preferably pure Ar gas, pure He gas, a mixed gas of the pure Ar gas and 1.5 volume% or less of O₂ or CO₂, or a mixed gas of the pure He gas and 1.5 volume% or less of O₂ or CO₂. On the other hand, a mixed gas of the pure Ar gas and more than 1.5 volume% of O₂ or CO₂ or a mixed gas of the pure He gas and more than 1.5 volume% of O₂ or CO₂, for example, a mixed gas of the pure Ar gas and 2.5 volume% or less of O₂ or CO₂ or a mixed gas of the pure He gas and 2.5 volume% or less of O₂ or CO₂, may be used. In this case, it is important to add two or more of Al, Ti, and Mg, which are deoxidizing compositions, in the wire with high content to decrease an amount of O₂ in the weld metal.

[0110] In particular, in a case in which a mixed gas of the pure Ar gas and more than 1.5 volume% of O₂ or CO₂ or a mixed gas of the pure He gas and more than 1.5 volume% of O₂ or CO₂ are used, it is preferable an amount of either one of Al, Ti, and Mg included in the wire is 70% or more of the upper limit of Al, Ti, and Mg defined in the present embodiments. For example, it is preferable to use a wire in which chemical compositions except the metal fluorides, the metal oxides, and the metal carbonates include, by mass%, with respect to the total mass of the flux-cored wire, one or more of 0.035% or more of Al, 0.07% or more of Ti, or 0.42% or more of Mg.

[Examples]

[0111] Hereinafter, the feasibility and effects of the present invention will be described in more detail using examples.

[0112] While being fed in the longitudinal direction, a steel strip was formed into an open tube by a forming roll and the flux was supplied from an opening portion of the open tube in the middle of the forming, and edge surfaces facing each other at the opening portion was subjected to butt seam welding to form a tube in which a slit-shaped gap did not exist. Annealing was applied to the tubulated wire in the middle of the wire-drawing to prepare a flux-cored wire having a final wire diameter of ϕ 1.2 mm. After the wire was prepared, a lubricant was applied onto the surface of the wire.

[0113] As an outer steel sheath (hoop), an outer steel sheath made of mild steel including C: 0.003%, Si: 0.03%, Mn: 0.11%, P: 0.006%, S: 0.003%, Al: 0.003%, and a remainder consisting of Fe and impurities, or an outer steel sheath made of Ni-containing steel shown in Table 1 was used. Here, all of % means mass% with respect to a total mass of the outer steel sheath.

[0114] In Tables 2-1, 2-3, 2-5, 2-7, 2-9, 2-11, 2-13, and 2-15, a plant oil was applied to all wires without a description of "PFPE oil applied". In addition, some of the wires were formed into tubes having a slit-shaped gap on which seam welding was not performed, and wire-drawn to prepare flux-cored wires having a wire diameter of ϕ 1.2 mm. In a case of a wire in which a slit-shaped gap existed, the entire wire was stored in a container in which the wire was able to be vacuum-packaged and stored in a dried state until welding was performed.

[0115] The flux-cored wire was analyzed in the following manner. The flux-cored wire was divided into an outer steel sheath and a flux by extracting the flux filling the wire from the wire. The metal compositions of the outer steel sheath were measured by chemical analysis. The constituents and compositions of the flux were quantitatively evaluated by X-ray diffraction and fluorescence X-ray analysis and then were separated into slag and an alloy using a concentration method such as flotation concentration or magnetic concentration, and each of the slag and alloy was analyzed by chemical analysis or gas analysis.

[0116] The chemical compositions of the prepared flux-cored wires are shown in Tables 2-1 to 2-16 and 3-1 to 3-16. In addition, in Tables 3-9, 3-11, 3-13, and 3-15, numbers of the hoop materials in Table 1 used for the outer steel sheath of the wire are also shown. The chemical compositions of the flux-cored wires shown in Tables 2-1 to 2-16 and 3-1 to 3-16 are results obtained by analyzing the wires by the above-described analyzing methods. The term "mass%" in Tables 2-1 to 2-16 and 3-1 to 3-16 means mass% with respect to a total mass of the wire (including the outer steel sheath and the flux). For example, Ni in Tables 3-1, 3-3, 3-5, and 3-7 is not contained in the outer steel sheath but contained completely as a Ni powder.

[0117] Using the flux-cored wires shown in Tables 2-1 to 2-16 and 3-1 to 3-16, the mechanical properties of the weld metal according to JIS Z 3111 (2005) were evaluated. That is, a method as shown in FIG. 8 (the symbol of the test plate 1.3) was used. A steel plate 1 (base metal number: P2) having a thickness of 20 mm shown in Table 6 was butted at a groove angle of 20° with a root opening of 16 mm, and using a backing metal 2. Weld bead is indicated by a symbol 3 in the drawing. As the steel plate 1 and the backing metal 2, SM 490A (JIS G 3106) was used. Buttering with two or more layers and with 3mm or more of excess weld metal was performed on the groove face of the steel plate 1 and the surface of the backing metal 2 using the flux-cored wire to be subjected to a test. Then, welding was performed with the first layer and the second layer being one or two passes the third layer to the last layer being two or three passes to prepare a test body. The welding conditions are shown in Tables 4-1 to 4-7 (the composition of the shielding gas is expressed by volume%). The welding conditions of the flux-cored wire using an outer steel sheath made of mild steel in Tables 2-1 to 2-8 and 3-1 to 3-8 are shown in Tables 4-1 to 4-4. As seen from Tables 4-1 to 4-4, welding was performed under the conditions of a current value of 280A, a voltage value of 25V, a welding rate of 30 cm/min, an interpass temperature of 150°C or less, and a flow rate of 25 l/min using any one of a pure Ar gas, a mixed gas of Ar with O₂ or CO₂, a pure He gas, and a mixed gas of He with O₂ or CO₂ as a shielding gas. The welding conditions of the flux-cored wires using an outer steel sheath made of Ni-containing steel in Tables 2-9 to 2-16 and 3-9 to 3-16 are shown in Tables 4-5 to 4-7. As seen from Tables 4-5 to 4-7, welding was performed under the conditions of a current value of 280A, a voltage value of 25V, a welding rate of 30 cm/min, an interpass temperature of 150°C or less, and a flow rate of 25 l/min using any one of a pure Ar gas, a mixed gas of Ar with O₂ or CO₂, a pure He gas, and a mixed gas of He with O₂ or CO₂ as a shielding gas.

[0118] The tensile strength and the Charpy absorbed energy of the weld metals were measured by collecting a A0 test piece (rod) 5 for tensile test according to JIS Z 3111 (2005) (having a diameter of 10 mm) and a Charpy impact test piece 4 (having a 2 mm V-notch) from the prepared test body as shown in FIG 8 as a mechanical test piece and performing mechanical property tests each of the test pieces. The results obtained by measuring and evaluating the mechanical properties obtained when the flux-cored wire using an outer steel sheath made of mild steel is used are shown in Tables 5-1 to 5-4, and the results obtained by measuring and evaluating the mechanical properties obtained when the flux-cored wire using an outer steel sheath made of Ni-containing steel is used are shown in Tables 5-5 to 5-8.

[0119] As seen from FIG. 6, as the evaluation of the mechanical properties when the flux-cored wire in which the outer steel sheath was made of mild steel was used, the test piece having the tensile strength of 660 MPa to 900 MPa and the toughness in which absorbed energy was 50J or more in the Charpy impact test at -196°C was accepted.

[0120] As seen from FIG. 7, as the evaluation of the mechanical properties when the flux-cored wire in which the outer steel sheath was made of Ni-containing steel was used, the test piece having the tensile strength of 660 MPa to 900 MPa and the toughness in which the absorbed energy was 69J or more in the Charpy impact test at - 196°C was accepted.

[0121] In addition, a test piece was collected from each of the obtained weld metals to measure an amount of oxygen in the weld metal. The amount of oxygen in the weld metal was measured by impulse heating furnace-inert gas melting infrared absorbing method. The measured amount of oxygen in each of the weld metals was shown in Tables 5-1 to 5-8.

[0122] In the wire of the present invention, the toughness was improved by reducing the amount of oxygen in the weld metal. Regarding the flux-cored wire in which the entire outer steel sheath was made of mild steel was used, the Charpy absorbed energy at -196°C was able to be secured in the weld metal including an amount of oxygen of 160 ppm or less. Further, regarding the flux-cored wire in which the entire outer steel sheath was made of Ni-containing steel was used, the Charpy absorbed energy at-196°C was able to be secured in the weld metal including an amount of oxygen of 80 ppm or less.

[0123] Next, regarding the flux-cored wire in which both the tensile strength and the Charpy absorbed energy at -196°C were acceptable in the evaluation results of Tables 5-1 to 5-8, the cold cracking resistance was evaluated. The cold cracking resistance was evaluated by the measurement of the amount of diffusible hydrogen and a y-groove weld cracking test. However, regarding the wire number B39 in Table 5-4, the amount of a Ca oxide was large and thus the amount of diffusible hydrogen was measured.

[0124] The amount of diffusible hydrogen was measured by gas chromatography according to JIS Z 3118 (method for measuring the amount of hydrogen in the steel weld portion) with the same welding conditions as in the mechanical property test. The measurement results of the amount of the diffusible hydrogen are shown in Tables 5-1 to 5-8.

[0125] The y-groove weld cracking test was performed using a steel plate (base metal number: P1) having a thickness of 25 mm shown in Table 6 under a predetermined atmosphere control of a temperature of 0°C and a humidity of 60% by a method according to JIS Z 3158 (y-groove weld cracking test) with the welding conditions of Tables 4-1 to 4-7.

[0126] The obtained y-groove weld cracking test results are shown in Tables 5-1 to 5-8. When the amount of diffusible hydrogen was 1.5 ml/100g or less, very high cold cracking resistance was demonstrated, since there was no cross-sectional cracking (i.e. no cross-sectional cracking was occurred) in all of the cross sections during y-groove weld cracking test even if the test temperature was 0°C and preheating was not performed.

[0127] As shown in the test results of Tables 5-1, 5-2, 5-5, and 5-6, the tensile strength, toughness, and cold cracking resistance of the samples made with wires with numbers A1 to A108, which were examples of the present invention, were all excellent, and the wires were acceptable. The sample regarding a wire with number A108 is an example in which a shielding gas is a mixed gas of pure Ar gas and 2.0 volume% of O₂. Since Al, Ti, and Mg, which are deoxidizing compositions, were sufficiently added to the wire with number A108, an amount of O₂ in the weld metal thereof was reduced and the sample regarding the wire with number A108 had excelent toughness.

[0128] On the other hand, as shown in the test results of Tables 5-3, 5-4,5-7, and 5-8, the samples made with wires with numbers of B1 to B101, which were comparative examples, did not satisfy the requirements defined in the present invention, and thus, one or more of the tensile strength, toughness, and cold cracking resistance were not able to be satisfied and the wires were not acceptable in the total determination. The wires of the wire Nos. B34, B34, B35. B46, B47, B48, B87, B88, B98, B99, and B100 satisfied requirements according to the present invention; however, since shielding gas were inappropriate, amounts of O₂ in the weld metals made with the wires were high, and thus, the toughness thereof were low.

TABLE 1

HOOP No.	CHEMICAL COMPOSITION OF OUTER STEEL SHEATH OF WIRE (mass% WITH RESPECT TO TOTAL MASS OF OUTER STEEL SHEATH)
	C	Si	Mn	P	S	Al	Ni
F1	0.010	0.03	0.1	0.007	0.004	0.012	6.0
F2	0.010	0.03	0.1	0.007	0.004	0.012	9.0
F3	0.010	0.03	0.1	0.007	0.004	0.012	12.5
F4	0.010	0.03	0.1	0.007	0.004	0.012	14.5
F5	0.020	0.15	0.2	0.007	0.004	0.002	12.5
F6	0.002	0.03	0.1	0.007	0.004	0.012	8.5

TABLE 2-1

WIRE No.	CATEGORY	REMARKS	FILLING RATE(%)	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]
				METAL FLUORIDE						METAL OXIDE
				CaF2	BaF2	SrF2	MgF2	LiF	TOTAL AMOUNT [α]	TiO2	SiO2	MgO	Al2O3	ZrO2	CaO	TOTAL AMOUNT [β]
A1	EXAMPLE		15.7	2.0					2.0	0.25	0.38				0.02	0.65
A2	EXAMPLE		21.8	7.0					7.0	0.22	0.25				0.02	0.49
A3	EXAMPLE	APPLIED PTFE	16.4	2.8					2.8	0.10	0.20				0.03	0.33
A4	EXAMPLE		18.7	3.7					3.7	0.40	0.48				0.02	0.90
A5	EXAMPLE		15.9	2.0					2.1	0.30	0.36				0.02	0.68
A6	EXAMPLE		19.5	6.0					6.0	0.10	0.30				0.02	0.42
A7	EXAMPLE	APPLIED PTFE	16.5	2.6					2.6	0.12	0.25				0.03	0.40
A8	EXAMPLE		18.6	4.8					4.8	0.15	0.22	0.12			0.02	0.51
A9	EXAMPLE		16.4	3.2					3.2	0.20	0.26		0.18		0.03	0.67
A10	EXAMPLE		16.5	3.5			0.2	0.1	3.8	0.15	0.25				0.03	0.43
A11	EXAMPLE		17.0	3.0					3.0	0.22	0.28		0.12		0.02	0.64
A12	EXAMPLE		16.8	3.6					3.6	0.16	0.36	0.12			0.02	0.66
A13	EXAMPLE		16.7	4.6	0.2	0.1		4.9	4.9	0.14	0.32				0.06	0.52
A14	EXAMPLE		16.3	4.5					4.5	0.34	0.34				0.02	0.70
A15	EXAMPLE		14.7	3.0					3.0	0.16	0.24	0.12	0.10		0.02	0.64
A16	EXAMPLE		19.9	2.9		0.2	0.1		3.2	0.36	0.20				0.02	0.58
A17	EXAMPLE		17.3	4.5					4.5	0.20	0.32				0.18	0.70
A18	EXAMPLE	APPLIED PTFE	16.5	3.2		0.1			3.3	0.12	0.32	0.20			0.02	0.66
A19	EXAMPLE		15.0	3. 6					3.6	0.26	0.25		0.12		0.02	0.65
A20	EXAMPLE		14.6	3.2	0.2				3.4	0.15	0.35	0.12			0.02	0.64
A21	EXAMPLE		14.1	3.3					3.3	0.12	0.22		0.25		0.02	0.61
A22	EXAMPLE		14.3	3.6					3.6	0.31	0.39				0.02	0.72
A23	EXAMPLE		18.5	3.2			0.2		3.4	0.18	0.46				0.02	0.66
A24	EXAMPLE		19.8	4.2	0.1			0.1	4.4	0.13	0.33	0.15	0.08		0.02	0.71
A25	EXAMPLE		18.5	4.0	0.1	0.1	0.1	0.1	4.4	0.16	0.21				0.02	0.39
A26	EXAMPLE		11.0	2.8					2.8	0.22	0.34				0.05	0.61
A27	EXAMPLE		17.8	4.0					4.0	0.12	0.20	0.10	0.12		0.05	0.59

TABLE 2-2

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]								α / β	CaF2 / α
	METAL CARBONATE						IRON POWDER	ARC STABILIZER
	CaCO3	BACO3	SrCO3	MgCO3	Li2CO3	TOTAL AMOUNT
A1	0.01					0.01		0.08	3.1	1.00
A2	0.01					0.01		0.08	14.3	1.00
A3	0.01					0.01		0.08	8.5	1.00
A4	0.01					0.01		0.08	4.1	1.00
A5	0.01					0.01		0.08	3.1	0.95
A6	0.01					0.01		0.08	14.3	1.00
A7	0.01					0.01		0.08	6.5	1.00
A8	0.01					0.01		0.08	9.4	1.00
A9	0.01					0.01		0.08	4.8	1.00
A10	0.01					0.01		0.08	8.8	0.92
A11		0.01				0.01		0.08	4.7	1.00
A12			0.01			0.01		0.08	5.5	1.00
A13				0.01		0.01		0.08	9.4	0.94
A14	0.01				0.01	0.02		0.08	6.4	1.00
A15	0.01					0.01	4.80	0.08	4.7	1.00
A16	0.01					0.01		0.08	5.5	0.91
A17	0.01	0.01				0.02		0.08	6.4	1.00
A18		0.01				0.01		0.08	5.0	0.97
A19		0.01				0.01		0.08	5.5	1.00
A20		0.01	0.01			0.02		0.08	5.3	0.94
A21			0.01			0.01	2.50	0.08	5.4	1.00
A22			0.01			0.01	1.50	0.08	5.0	1.00
A23			0.01			0.01		0.08	5.2	0.94
A24				0.01		0.01		0.10	6.2	0.95
A25					0.01	0.01		0.10	11.3	0.91
A26					0.01	0.01		0.10	4.6	1.00
A27					0.01	0.01		0.10	6.8	1.00

TABLE 2-3

WIRE No.	CATEGORY	REMARKS	FILLING RATE(%)	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]
				METAL FLUORIDE						METAL OXIDE
				CaF2	BaF2	SrF2	MgF2	LiF	TOTAL AMOUNT [α]	TiO2	SiO2	MgO	Al2O3	ZrO2	CaO	TOTAL AMOUNT [β]
A28	EXAMPLE		14.1	2.5				0.1	2.6	0.25	0.40				0.01	0.67
A29	EXAMPLE		16.3	4.8		0.1			4.9	0.12	0.24	0.05		0.02	0.02	0.43
A30	EXAMPLE	APPLIED PTFE	16. 7	2.4	0.2				2.6	0.18	0.25	0.12	0.10		0.02	0.67
A31	EXAMPLE		18.9	4.6			0.1	0.2	4.9	0.10	0.22				0.12	0.44
A32	EXAMPLE		13.8	3.0					3.0	0.12	0.32				0.02	0.46
A33	EXAMPLE		18.5	4.5					4.5	0.15	0.35				0.02	0.52
A34	EXAMPLE	APPLIED PTFE	14.0	2.9		0.1		0.1	3.1	0.20	0.28		0.12		0.02	0.62
A35	EXAMPLE		18.6	4.6					4.6	0.15	0.33	0.15			0.02	0.65
A36	EXAMPLE		13.0	3.0					3.0	0.15	0.32		0.10		0.02	0.59
A37	EXAMPLE		13.3	3.2					3.2	0.20	0.35				0.02	0.57
A38	EXAMPLE		14.5	4.5					4.5	0.15	0.30	0.23			0.02	0.70
A39	EXAMPLE		16.0	5.8					5.8	0.20	0.35				0.02	0.57
A40	EXAMPLE		17.8	4.0					4.0	0.15	0.30				0.02	0.47
A41	EXAMPLE		17.9	4.0					4.0	0.15	0.30				0.02	0.47
A42	EXAMPLE		17.6	4.0					4.0	0.15	0.30				0.02	0.47
A43	EXAMPLE	APPLIED PTFE	18.6	4.0					4.0	0.15	0.30				0.02	0.47
A44	EXAMPLE		18.2	4.0					4.0	0.15	0.30				0.02	0.47
A45	EXAMPLE		18.0	4.0					4.0	0.15	0.30				0.19	0.64
A46	EXAMPLE		19.0	5.0					5.0	0.15	0.30				0.19	0.64
A47	EXAMPLE		16.9	3.6					3.6	0.11	0.22	0.12			0.02	0.47
A48	EXAMPLE		16.0	4.2	0.2	0.1			4.5	0.14	0.32				0.06	0.52
A49	EXAMPLE	APPLIED PTFE	17.9	3.8					3.8	0.34	0.34				0.02	0.70
A50	EXAMPLE		17.6	4.0			0.4		4.4	0.01	0.20			0.10	0.02	0.33
A51	EXAMPLE		16.8	3.1					3.1	0.01	0.20					0.21
A52	EXAMPLE		18.2	4.5					4.5	0.01	0.20		0.10		0.02	0.33
A53	EXAMPLE	APPLIED PTFE	20.2	5.8					5.8	0.01	0.20	0.10		0.10	0.02	0.43
A54	EXAMPLE		16.5	3.0					3.0	0.06	0.30				0.02	0.38
A55	EXAMPLE		17.5	2.8					2.8	0.05	0.20				0.02	0.27

TABLE 2-4

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]								α / β	CaF2 / α
	METAL CARBONATE						IRON POWDER	ARC STABILIZER
	CaCO3	BaCO3	SrCO3	MgCO3	Li2CO3	TOTAL AMOUNT
A28					0.01	0.01		0.10	3.9	0.96
A29	0.01					0.01		0.10	11.4	0.98
A30	0.01					0.01		0.10	3.9	0.92
A31	0.01					0.01		0.10	11.1	0.94
A32	0.01					0.01		0.10	6.5	1.00
A33	0.01					0.01		0.10	8.7	1.00
A34	0.01					0.01		0.10	5.0	0.94
A35	0.01					0.01		0.10	7.1	1.00
A36	0.01					0.01		0.10	5.1	1.00
A37	0.01					0.01		0.10	5.6	1.00
A38	0.01					0.01		0.10	6.4	1.00
A39	0.01					0.01		0.10	10.2	1.00
A40	0.01					0.01		0.10	8.5	1.00
A41	0.01					0.01		0.10	8.5	1.00
A42	0.01					0.01		0.10	8.5	1.00
A43	0.01					0.01	0.10	0.10	8.5	1.00
A44	0.44			0.10	0.05	0.59	0.60	0.10	8.5	1.00
A45	0.01					0.01		0.10	6.3	1.00
A46	0.41					0.01		0.10	7.8	1.00
A47	0.01					0.01		0.08	7.7	1.00
A48	0.01					0.01		0.08	8.7	0.93
A49	0.01					0.01		0.08	5.4	1.00
A50	0.01					0.01		0.08	13.3	0.91
A51	0.01					0.01		0.08	14.8	1.00
A52	0.01					0.01		0.08	13.6	1.00
A53	0.01					0.01		0.08	13.5	1.00
A54	0.01					0.01		0.08	7.9	1.00
A55	0.01					0.01		0.08	10.4	1.00

TABLE 2-6

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]								α / β	CaF2 / α
	METAL CARBONATE						IRON POWDER	ARC STABILIZER
	CaCO3	BaCO3	SrCO3	MgCO3	Li 2CO3	TOTAL AMOUNT
B1	0.01					0.01		0.08	4.9	1.00
B2	0.01					0.01		0.08	15.5	1.00
B3	0.01					0.01		0.08	3.7	1.00
B4	0.01					0.01		0.08	10.9	1.00
B5	0.01					0.01		0.08	4.8	1.00
B6	0.01					0.01		0.08	5.8	1.00
B7	0.01					0.01		0.08	5.4	1.00
B8	0.01					0.01		0.08	2.8	1.00
B9		0.01				0.01		0.08	15.3	1.00
B10			0.01			0.01		0.08	8.7	0.81
B11				0.01		0.01		0.08	4.7	1.00
B12	0.01				0.01	0.02		0.08	6.4	1.00
B13	0.01					0.01		0.08	6.7	0.97
B14	0.01					0.01		0.08	4.2	0.93
B15	0.01	0.01				0.02		0.08	6.0	0.97
B16		0.01				0.01		0.08	5.9	1.00
B17		0.01				0.01		0.08	5.7	0.97
B18		0.01	0.01			0.02		0.08	6.1	1.00
B19			0.01			0.01		0.08	6.2	0.95
B20			0.01			0.01		0.08	5.1	1.00
B21			0.01			0.01	3.00	0.08	5.3	0.94
B22				0.01		0.01		0.08	6.0	1.00
B23					0.01	0.01		0.08	7.3	0.94
B24					0.01	0.01		0.08	5.7	1.00
B25					0.01	0.01		0.08	4.4	0.97

TABLE 2-8

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]								α / β	CaF2/ α
	METAL CARBONATE						IRON POWDER	ARC STABILIZER
	CaCO3	BaCO3	SrCO3	MgCO3	Li2CO3	TOTAL AMOUNT
B26					0.01	0.01		0.08	5.1	0.94
B27	0.01					0.01		0.08	4.5	1.00
B28	0.01					0.01		0.08	6.8	0.94
B29	0.01					0.01		0.08	6.7	0.97
B30	0.01					0.01		0.08	7.1	0.94
B31	0.01					0.01		0.08	6.2	0.97
B32	0.01					0.01		0.08	5.7	0.93
B33	0.01					0.01		0.08	5.6	1.00
B34	0.01					0.01		0.08	4.7	0.96
B35	0.01					0.01		0.08	12.1	0.98
B36	0.01					0.01		0.03	12.5	1.00
B37	0.01					0.01		0.09	11.4	1.00
B38	0.01					0.01		0.09	11.4	1.00
B39	0.01					0.01		0.09	4.6	1.00
B40	0.50			0.10	0.05	0.65	0.65	0.09	11.4	1.00
B41	0.01					0.01		0.09	5.1	0.95
B42	0.01					0.01		0.09	4.9	0.94
B43	0.01					0.01		0.09	13.2	0.93
B44	0.01					0.01		0.60	7.4	0.95
B45	0.01					0.01		0.08	7.6	0.94
B46	0.01					0.01		0.08	11.8	1.00
B47	0.01					0.01		0.08	9.3	0.90
B48	0.01					0.01		0.08	4.7	1.00
B49	1.01					1.01		1.08	6.3	1.00
B50	0.02					0.02	1.00	0.08	14.4	0.92
B51	0.02					0.02	5.50	0.08	10.4	0.92

TABLE 2-9

WIRE No.	CATEGORY	REMARKS	FILLING RATE(%)	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]
				METAL FLUORIDE						METAL OXIDE
				CaF2	BaF2	SrF2	MgF2	LiF	TOTAL AMOUNT [α]	TiO2	SiO2	MgO	Al2O3	ZrO2	CaO	TOTAL AMOUNT [β]
A56	EXAMPLE		8.0	2.0					2.0	0.15	0.32				0.02	0.49
A57	EXAMPLE		14.0	7.0					7.0	0.15	0.32				0.02	0.49
A58	EXAMPLE		8.0	4.5					4.5	0.10	0.20				0.02	0.32
A59	EXAMPLE		8.0	2.7					2.7	0.40	0.47				0.03	0.90
A60	EXAMPLE		8.0	4.0					4.0	0.20	0.35				0.03	0.58
A61	EXAMPLE		8.0	3.5		0.2		0.1	3.8	0.20	0.35				0.03	0.58
A62	EXAMPLE		6.0	4.4	0.1				4.5	0.10	0.28				0.02	0.40
A63	EXAMPLE		8.0	3.2					3.2	0.10	0.30				0.02	0.42
A64	EXAMPLE	APPLIED PTFE	8.0	2.8					2.8	0.12	0.28				0.03	0.43
A65	EXAMPLE		8.0	2.8					2.8	0.30	0.25	0.15			0.03	0.73
A66	EXAMPLE		8.0	3.4					3.4	0.15	0.30	0.10	0.10		0.03	0.68
A67	EXAMPLE		8.0	3.4			0.1	0.1	3.6	0.24	0.32		0.15		0.03	0.74
A68	EXAMPLE		8.0	3.7			0.2		3.9	0.24	0.25				0.10	0.59
A69	EXAMPLE		8.0	4.0					4.0	0.15	0.36				0.03	0.54
A70	EXAMPLE		5.5	4.3					4.3	0.35	0.35	0.15			0.03	0.88
A71	EXAMPLE		10.0	3.8					3.8	0.24	0.28				0.02	0.54
A72	EXAMPLE		11.0	3.8		0.1		0.1	4.0	0.34	0.20				0.02	0.56
A73	EXAMPLE		12.0	3.8					3.8	0.10	0.23		0.24		0.05	0.62
A74	EXAMPLE	APPLIED PTFE	9.0	4.8	0.1	0.1			5.0	0.18	0.24	0.22			0.02	0.66
A75	EXAMPLE		8.0	5.6	0.2				5.8	0.12	0.23	0.10	0.12		0.02	0.59
A76	EXAMPLE		10.0	6.0					6.0	0.13	0.22	0.15			0.03	0.53
A77	EXAMPLE		12.0	6.3					6.3	0.15	0.33		0.05		0.03	0.56
A78	EXAMPLE		12.0	4.6					4.6	0.24	0.35	0.11			0.03	0.73
A79	EXAMPLE		11.0	4.9					4.9	0.18	0.34				0.02	0.54
A80	EXAMPLE		8.0	4.7	0.2	0.1	0.1	0.1	5.2	0.20	0.22	0.12	0.10		0.05	0.69

TABLE 2-10

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]								α/β	CaF2/ α
	METAL CARBONATE						IRON POWDER	ARC STABILIZER
	CaCO3	BaCO3	SrCO3	MgCO3	Li 2CO3	TOTAL AMOUNT
A56	0.01					0.01	3.8	0.09	4.1	1.00
A57	0.01					0.01	4.8	0.09	14.3	1.00
A58	0.01					0.01	2.6	0.09	14.1	1.00
A59	0.01					0.01	2.8	0.09	3.0	1.00
A60	0.01					0.01	2.8	0.09	6.9	1.00
A61	0.01					0.01	2.6	0.09	6.6	0.92
A62	0.01					0.01	1.9	0.09	11.3	0.98
A63	0.01					0.01	3.6	0.08	7.6	1.00
A64	0.01					0.01	4.2	0.08	6.5	1.00
A65	0.01					0.01	3.6	0.08	3.8	1.00
A66	0.01					0.01	3.2	0.08	5.0	1.00
A67	0.01					0.01	2.5	0.08	4.9	0.94
A68	0.01					0.01	2.7	0.08	6.6	0.95
A69	0.01					0.01	2.7	0.08	7.4	1.00
A70	0.01					0.01	1.2	0.08	4.9	1.00
A71	0.01					0.01		0.08	7.0	1.00
A72		0.01				0.01	2.4	0.08	7.1	0.95
A73		0.01				0.01	2.7	0.08	6.1	1.00
A74		0.01				0.01	1.2	0.08	7.6	0.96
A75		0.01				0.01		0.08	9.8	0.97
A76		0.01				0.01		0.08	11.3	1.00
A77		0.01				0.01		0.08	11.3	1.00
A78		0.01				0.01	1.6	0.08	6.3	1.00
A79			0.01			0.01	1.2	0.08	9.1	1.00
A80				0.01		0.01		0.08	7.5	0.90

TABLE 2-12

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]								α / β	CaF2 / α
	METAL CARBONATE						IRON POWDER	ARC STABILIZER
	CaCO3	BaCO3	SrCO3	MgCO3	Li2CO3	TOTAL AMOUNT
A81					0.01	0.01	4.5	0.08	9.0	1.00
A82	0.01					0.01		0.08	10.2	1.00
A83		0.01				0.01		0.08	11.3	1.00
A84		0.01				0.01	1.4	0.08	11.2	0.96
A85			0.01			0.01	1.1	0.08	10.8	1.00
A86			0.01			0.01	1.7	0.08	7.2	0.98
A87				0.01		0.01	1.2	0.08	7.9	0.96
A88					0.01	0.01	3.6	0.08	7.5	1.00
A89	0.01					0.01	3.3	0.08	9.8	0.98
A90		0.01				0.01	1.6	0.08	7.4	1.00
A91		0.01				0.01	3.9	0.08	5.5	1.00
A92			0.01			0.01	0.6	0.08	10.4	1.00
A93			0.01			0.01	2.6	0.08	4.1	0.97
A94				0.01		0.01	0.6	0.08	7.0	1.00
A95					0.01	0.01	2.2	0.08	6.5	1.00
A96	0.01					0.01	2.2	0.08	8.9	1.00
A97		0.01				0.01	2.6	0.08	6.6	1.00
A98		0.01				0.01	2.5	0.08	10.5	1.00
A99	0.50	0.02	0.02	0.02	0.02	0.58	1.6	0.08	10.0	1.00
A100	0.01					0.01	3.1	0.08	5.3	1.00
A101	0.01					0.01	2.6	0.08	14.6	1.00
A102	0.01			0.10		0.11	2.1	0.08	11.3	0.91
A103	0.01					0.01	2.4	0.08	13.9	0.94
A104	0.01				0.10	0.11	2.2	0.08	13.5	0.94
A105	0.01					0.01		0.08	13.5	1.00
A106	0.01					0.01		0.08	13.6	1.00
A107	0.01					0.01	3.9	0.09	10.3	1.00
A108	0.01					0.01	0.7	0.08	14.3	1.00

TABLE 2-14

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]								α / β	CaF2/ α
	METAL CARBONATE						IRON POWDER	ARC STABILIZER
	CaCO3	BaCO3	SrCO3	MgCO3	Li2CO3	TOTAL AMOUNT
B52	0.01					0.01	5.3	0.09	5.0	1.00
B53	0.01					0.01		0.09	13.4	1.00
B54	0.01					0.01	3.3	0.09	24.3	0.83
B55	0.01					0.01	3.9	0.09	3.7	1.00
B56	0.01					0.01	3.1	0.09	10.3	1.00
B57	0.01					0.01	3.0	0.09	5.1	1.00
B58	0.01					0.01	2.4	0.09	5.4	1.00
B59	0.01					0.01		0.09	5.4	1.00
B60	0.01					0.01	3.9	0.09	2.7	1.00
B61	0.01					0.01	0.5	0.09	15.6	0.93
B62	0.01					0.01	1.2	0.09	10.2	0.82
B63	0.01					0.01	2.3	0.09	6.8	0.95
B64	0.01					0.01	2.0	0.09	6.5	1.00
B65	0.01					0.01	2.7	0.09	7.8	1.00
B66	0.01					0.01	2.5	0.09	5.3	0.93
B67		0.01				0.01	2.7	0.09	6.7	1.00
B68		0.01				0.01	2.1	0.09	4.3	0.95
B69		0.01				0.01	1.5	0.09	7.5	1.00
B70		0.01				0.01	2.4	0.09	6.2	0.95
B71		0.01				0.01	2.1	0.09	5.5	1.00
B72		0.01				0.01	2.4	0.09	5.8	0.95
B73		0.01				0.01	2. 1	0.09	8.7	1.00
B74			0.01			0.01	2.2	0.09	7.6	1.00
B75				0.01		0.01	2.3	0.09	6.4	0.97

TABLE 2-16

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]								α / β	CaF2/ α
	METAL CARBONATE						IRON POWDER	ARC STABILIZER
	CaCO3	BaCO3	SrCO3	MgCO3	Li2CO3	TOTAL AMOUNT
B76					0.01	0.01	1.7	0.09	7.0	1.00
B77	0.01					0.01	2.4	0.09	7.0	0.95
B78		0.01				0.01	2.7	0.09	8.9	0.53
B79		0.01				0.01	2.2	0.09	6.3	1.00
B80			0.01			0.01	2.4	0.09	6.2	0.95
B81			0.01			0.01	1.8	0.09	6.5	1.00
B82				0.01		0.01	1.8	0.08	6.6	1.00
B83					0.01	0.01	1.7	0.09	7.5	0.95
B84	0.01					0.01	2.5	0.09	6.5	0.95
B85		0.01				0.01	1.5	0.09	8.1	0.95
B86						0.00	5.4	0.09	3.6	0.96
B87						0.00	3.2	0.09	4.9	1.00
B88						0.00	0.4	0.09	9.2	1.00
B89						0.00	1.0	0.09	9.2	1.00
B90						0.00	1.5	0.09	5.4	1.00
B91	0. 65				0.01	0.66	1.2	0.09	8.6	1.00
B92						0.00	5.0	0.09	4.1	0.95
B93						0.00	5.2	0.09	4.0	0.94
B94					0.05	0.05	4.3	0.09	14.4	0.93
B95			0.01			0.01	1.5	0.09	12.9	0.97
B96	0.01					0.01	3.2	0.60	8.9	0.96
B97	0.01					0.01	0.3	0.10	12.0	0.93
B98	0.01			0.10		0.11	1.6	0.10	8.2	0.95
B99	0.01					0.01	3.8	0.09	10.9	1.00
B100	0.01				0.10	0.11	3.0	0.09	8.9	0.95
B101	0.01				0.10	0.11	3.0	0.09	14.7	0.92

TABLE 3-1

WIRE No.	CATEGORY	CHEMICAL COMPOSITION OF ALLOY OF WIRE [mass% WITH RESPECT TO TOTAL MASS OF WIRE]
		C	Si	Mn	P	S	Al	Ni
A1	EXAMPLE	0.015	0.10	0.2	0.007	0.004	0.012	13.0
A2	EXAMPLE	0.015	0.10	0.2	0.007	0.004	0.012	14.0
A3	EXAMPLE	0.020	0.25	0.5	0.007	0.004	0.012	13.0
A4	EXAMPLE	0.020	0.25	0.5	0.007	0.004	0.012	14.0
A5	EXAMPLE	0.025	0.30	0.7	0.007	0.004	0.012	13.0
A6	EXAMPLE	0.025	0.30	0.7	0.007	0.004	0.012	13.0
A7	EXAMPLE	0.003	0.20	0.5	0.006	0.003	0.010	13.0
A8	EXAMPLE	0.040	0.20	0.5	0.006	0.003	0.010	13.0
A9	EXAMPLE	0.015	0.05	0.5	0.006	0.003	0.012	12.0
A10	EXAMPLE	0.015	0.40	0.5	0.006	0.003	0.012	12.0
A11	EXAMPLE	0.020	0.15	0.2	0.006	0.003	0.010	13.0
A12	EXAMPLE	0.020	0.15	0.8	0.006	0.003	0.010	12.0
A13	EXAMPLE	0.025	0.10	0.6	0.006	0.003	0.003	11.0
A14	EXAMPLE	0.025	0.10	0.6	0.006	0.003	0.050	11.0
A15	EXAMPLE	0.030	0.20	0.5	0.006	0.003	0.012	6.0
A16	EXAMPLE	0.030	0.20	0.5	0.006	0.003	0.012	16.0
A17	EXAMPLE	0.010	0.10	0.4	0.006	I 0.003	0.010	11.5
A18	EXAMPLE	0.010	0.10	0.4	0.006	0.003	0.010	11.5
A19	EXAMPLE	0.015	0.20	0.5	0.006	0.003	0.006	10.0
A20	EXAMPLE	0.015	0.20	0.5	0.006	0.003	0.006	10.0
A21	EXAMPLE	0.030	0.10	0.4	0.006	0.003	0.008	7.5
A22	EXAMPLE	0.030	0.10	0.4	0.006	0.003	0.008	7.5
A23	EXAMPLE	0.005	0.15	0.3	0.006	0.003	0.010	14.0
A24	EXAMPLE	0.010	0.30	0.3	0.006	0.003	0.010	14.0
A25	EXAMPLE	0.010	0.30	0.4	0.006	0.003	0.008	13.0
A26	EXAMPLE	0.010	0.15	0.3	0.006	0.003	0.015	7.5
A27	EXAMPLE	0.015	0.15	0.3	0.006	0.003	0.015	12.5

TABLE 3-2

WIRE No.	CHEMICAL COMPOSITION OF ALLOY OF WIRE [mass% WITH RESPECT TO TOTAL MASS OF WIRE]									SM (%)	Ceq (%)
	Cu	Cr	Mo	V	Ti	Nb	B	Mg	REM
A1										0.30	0.378
A2	0.2									30	0.403
A3	0.2									0.75	0.439
A4										0.75	0.464
A5										1.00	0.479
A6										1.00	0.479
A7	0.2							0.2		0.70	0.420
A8	0.2									0.70	0.457
A9	0.3				0.10					0.55	0.400
A10			0.2							0.90	0.465
A11		0.2			0.03					0.35	0.425
A12	0.2					0.02		0.2		0.95	0.460
A13	0.2						0.001			0.70	0.404
A14										0.70	0.404
A15	0.2									0.70	0.272
A16					0.02					0.70	0.522
A17	0.5									0.50	0.368
A18		0.5		0.10				0.4		0.50	0.475
A19	0.2		0.5							0.70	0.482
A20	0.1			0.20				0.2		0.70	0.371
A21					0.10					0.50	0.288
A22	0.1		0.3			0.10		0.4		0.50	0.363
A23	0.1	0.2			0.02		0.010			0.45	0.451
A24								0.6		0.60	0.423
A25	0.2	0.1	0.1	0.05	0.02	0.01	0.002	0.1		0.70	0.463
A26					0.02					0.45	0.254
A27		0.2	0.4							0.45	0.524

TABLE 3-3

WIRE No.	CATEGORY	CHEMICAL COMPOSITION OF ALLOY OF WIRE [mass% WITH RESPECT TO TOTAL MASS OF WIRE]
		C	Si	Mn	P	S	Al	Ni
A28	EXAMPLE	0.020	0.10	0.8	0.006	0.003	0.030	10.5
A29	EXAMPLE	0.020	0.40	0.5	0.006	0.003	0.030	10.5
A30	EXAMPLE	0.015	0.25	0.4	0.006	0.003	0.012	13.0
A31	EXAMPLE	0.015	0.25	0.4	0.006	0.003	0.012	13.0
A32	EXAMPLE	0.020	0.15	0.5	0.006	0.003	0.008	10.0
A33	EXAMPLE	0.020	0.15	0.5	0.006	0.003	0.008	13.0
A34	EXAMPLE	0.020	0.20	0.5	0.006	0.003	0.008	10.0
A35	EXAMPLE	0.020	0.20	0.5	0.006	0.003	0.008	13.0
A36	EXAMPLE	0.010	0.10	0.6	0.006	0.003	0.008	9.0
A37	EXAMPLE	0.010	0.30	0.4	0.006	0.003	0.008	9.0
A38	EXAMPLE	0.030	0.10	0.6	0.006	0.003	0.008	9.0
A39	EXAMPLE	0.030	0.30	0.4	0.006	0.003	0.008	9.0
A40	EXAMPLE	0.020	0.20	0.5	0.006	0.003	0.008	13.0
A41	EXAMPLE	0.020	0.20	0.5	0.006	0.003	0.008	13.0
A42	EXAMPLE	0.020	0.20	0.5	0.006	0.003	0.008	13.0
A43	EXAMPLE	0.035	0.30	0.7	0.006	0.003	0.008	14.0
A44	EXAMPLE	0.020	0.20	0.5	0.006	0.003	0.008	13.0
A45	EXAMPLE	0.020	0.20	0.5	0.006	0.003	0.008	13.0
A46	EXAMPLE	0.020	0.20	0.5	0.006	0.003	0.008	13.0
A47	EXAMPLE	0.020	0.10	0.8	0.006	0.003	0.030	12.5
A48	EXAMPLE	0.020	0.40	0.5	0.006	0.003	0.030	10.5
A49	EXAMPLE	0.015	0.25	0.4	0.006	0.003	0.012	13.0
A50	EXAMPLE	0.030	0.08	0.4	0.006	0.004	0.011	12.8
A51	EXAMPLE	0.030	0.11	0.4	0.006	0.004	0.011	13.1
A52	EXAMPLE	0.030	0.08	0.4	0.006	0.004	0.011	13.3
A53	EXAMPLE	0.030	0.12	0.4	0.006	0.004	0.011	13.5
A54	EXAMPLE	0.015	0.25	0.3	0.008	0.004	0.010	13.0
A55	EXAMPLE	0.015	0.10	0.5	0.008	0.004	0.010	14.0

TABLE 3-4

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]									SM (%)	Ceq (%)
	Cu	Cr	Mo	V	Ti	Nb	B	Mg	REM
A28	0.2				0.01		0.002			0.90	0.420
A29	0.2				0.01	0.01		0.2		0.90	0.383
A30	0.2		0.1	0.05						0.65	0.446
A31	0.2	0.1	0.1		0.04					0.65	0.462
A32	0.2									0.65	0.360
A33	0.2							0.2		0.65	0.435
A34	0.2				0.01					0.70	0.362
A35	0.2				0.01					0.70	0.437
A36			0.3							0.70	0.414
A37	0.2	0.2			0.01					0.70	0.354
A38	0.2									0.70	0.359
A39			0.1	0.04				0.4		0.70	0.362
A40	0.2			0.03	0.01					0.70	0.439
A41	0.2			0.03	0.01				0.050	0.70	0.439
A42					0.01				0.010	0.70	0.437
A43									0.001	1.00	0.514
A44				0.05	0.01					0.70	0.440
A45	0.2				0.01					0.70	0.437
A46	0.2				0.01					0.70	0.437
A47	0.2				0.01		0.002			0.90	0.470
A48	0.2				0.01	0.01		0.2		0.90	0.383
A49	0.2		0.1	0.05						0.65	0.446
A50					0.02					0.48	0.420
A51					0.02			0.3		0.51	0.429
A52					0.02					0.48	0.433
A53					0.02			0.4		0.52	0.439
A54										0.55	0.400
A55	0.3									0.60	0.453

TABLE 3-6

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]									SM (%)	Ceq (%)
	Cu	Cr	Mo	V	Ti	Nb	B	Mg	REM
B1										0.50	0.306
B2										0.65	0.325
B3										0.65	0.435
B4	0.2									0.55	0.405
B5										0.40	0.377
B6										0.65	0.455
B7										0.55	0.410
B8	0.2									0.60	0.425
B9	0.3				0.02					0.65	0.392
B10										0.65	0.392
B11	0.2	0.1			0.02					0.60	0.422
B12	0.2									0.60	0.445
B13		0.1	0.2	0.05						0.33	0.427
B14	0.3				0.02		0.003	0.3		0.78	0.373
B15	0.3		0.2							0.20	0.391
B16								0.2		1.00	0.474
B17		0.1			0.05	0.02				0.70	0.352
B18	0.2	0.2		0.10			0.004			0.70	0.379
B19	0.2		0.2					0.2		0.65	0.435
B20	0.1		0.1	0.03	0.02					0.65	0.412
B21				0.04		0.01				0.70	0.270
B22	0.6	0.1					0.003	0.2		0.70	0.349
B23		0.6			0.02					0.65	0.425
B24	0.2		0.6		0.03			0.4		0.65	0.480
B25	0.2	0.1		0. 30		0.02				0.65	0.414

TABLE 3-8

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]									SM (%)	Ceq (%)
	Cu	Cr	Mo	V	Ti	Nb	B	Mg	REM
B26	0.1				0.15			0.3		0.65	0.385
B27	0.3	0.1	0.2			0.15				0.60	0.395
B28				0.05			0.012			0.50	0.412
B29	0.2		0.2		0.02			0.7		0.40	0.407
B30	0.2									0.25	0.388
B31				0.08						1.10	0.412
B32	0.2					0.02				0.35	0.235
B33		0.2	0.3							0.70	0.552
B34	0.2		0.1		0.02		0.004			0.65	0.330
B35		0.1		0.03				0.2		0.60	0.450
B36	0.3				0.01					0.76	0.403
B37	0.4						0.002			0.72	0.411
B38	0.4								0.06	0.70	0.392
B39	0.4									0.80	0.481
B40	0.4									0.85	0.423
B41	0.4									0.80	0.448
B42	0.4									0.75	0.383
B43	0.4									0.85	0.383
B44	0.4									0.80	0.401
B45	0.4									0.80	0.551
B46										0.40	0.377
B47										0.65	0.455
B48	0.3									0.60	0.440
B49	0.2									0.55	0.400
B50	0.2									0.55	0.400
B51	0.2					0.04		0.4	0.02	0.55	0.350

TABLE 3-9

WIRE No.	CATEGORY	HOOP No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]
			C	Si	Mn	P	S	Al	Ni
A56	EXAMPLE	F4	0.010	0.15	0.4	0.006	0.004	0.011	14.5
A57	EXAMPLE	F4	0.010	0.15	0.4	0.006	0.004	0.011	13.3
A58	EXAMPLE	F4	0.020	0.15	0.3	0.006	0.004	0.011	13.3
A59	EXAMPLE	F4	0.020	0.15	0.3	0.006	0.004	0.011	14.5
A60	EXAMPLE	F4	0.030	0.10	0.2	0.006	0.004	0.011	13.3
A61	EXAMPLE	F4	0.030	0.40	0.6	0.006	0.004	0.011	13.3
A62	EXAMPLE	F6	0.003	0.20	0.5	0.006	0.004	0.011	7.8
A63	EXAMPLE	F3	0.040	0.20	0.4	0.006	0.004	0.011	11.5
A64	EXAMPLE	F3	0.015	0.05	0.4	0.006	0.004	0.011	11.5
A65	EXAMPLE	F3	0.015	0.40	0.3	0.006	0.004	0.011	11.5
A66	EXAMPLE	F3	0.015	0.20	0.2	0.006	0.004	0.011	11.5
A67	EXAMPLE	F3	0.015	0.15	0.8	0.006	0.004	0.011	11.5
A68	EXAMPLE	F5	0.030	0.18	0.5	0.006	0.004	0.011	11.5
A69	EXAMPLE	F5	0.030	0.18	0.5	0.006	0.004	0.003	11.5
A70	EXAMPLE	F1	0.030	0.15	0.5	0.006	0.004	0.011	6.0
A71	EXAMPLE	F4	0.030	0.15	0.5	0.006	0.004	0.011	16.0
A72	EXAMPLE	F4	0.025	0.15	0.4	0.006	0.004	0.011	13.3
A73	EXAMPLE	F4	0.015	0.15	0.3	0.006	0.004	0.011	13.3
A74	EXAMPLE	F3	0.015	0.20	0.3	0.006	0.004	0.011	11.5
A75	EXAMPLE	F4	0.025	0.20	0.4	0.006	0.004	0.011	13.8
A76	EXAMPLE	F4	0.025	0.25	0.3	0.006	0.004	0.011	13.9
A77	EXAMPLE	F4	0.025	0.25	0.3	0.006	0.004	0.011	13.6
A78	EXAMPLE	F4	0.025	0.30	0.3	0.006	0.004	0.011	13.3
A79	EXAMPLE	F4	0.025	0.30	0.3	0.006	0.004	0.011	13.3
A80	EXAMPLE	F2	0.010	0.20	0.5	0.006	0.004	0.011	9.0
A81	EXAMPLE	F2	0.010	0.20	0.2	0.006	0.004	0.011	8.3

TABLE 3-10

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]									SM (%)	Ceq (%)
	Cu	Cr	Mo	V	Ti	Nb	B	Mg	REM
A56										0.55	0.445
A57										0.55	0.415
A58	0.2									0.45	0.409
A59										0.45	0.439
A60	0.1	0.2		0.02						0.30	0.441
A61			0.1							1.00	0.504
A62	0.2	0.3			0.03					0.70	0.350
A63	0.2									0.60	0.403
A64				0.01			0.004	0.2		0.45	0.372
A65		0.1	0.1							0.70	0.414
A66	0.2		0.2			0.02				0.40	0.394
A67	0.1							0.2		0.95	0.442
A68						0.01		0.4		0.68	0.408
A69		0.2		0.06						0.68	0.453
A70	0.2		0.3	0.05	0.02					0.65	0.348
A71	0.2				0.02		0.004	0.2		0.65	0.520
A72	0.5									0.55	0.430
A73		0.5								0.45	0.504
A74	0.2		0.5		0.01					0.50	0.486
A75	0.1	0.2	0.1	0.20						0.60	0.524
A76	0.2		0.1		0.10					0.55	0.458
A77				0.04		0.10	0.003	0.2		0.55	0.428
A78	0.2						0.010	0.3		0.60	0.420
A79			0.2		0.03			0.6		0.60	0.470
A80	0.2	0.2	0.1	0.04	0.02	0.01	0.001	0.2		0.70	0.395
A81	0.2									0.40	0.259

TABLE 3-11

WIRE No.	CATEGORY	HOOP No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]
			C	Si	Mn	P	S	Al	Ni
A82	EXAMPLE	F4	0.020	0.20	0.5	0.006	0.004	0.011	13.3
A83	EXAMPLE	F3	0.025	0.20	0.5	0.006	0.004	0.011	11.8
A84	EXAMPLE	F3	0.030	0.30	0.6	0.006	0.004	0.011	11.5
A85	EXAMPLE	F2	0.015	0.30	0.4	0.006	0.004	0.011	8.3
A86	EXAMPLE	F4	0.015	0.15	0.4	0.006	0.004	0.011	13.3
A87	EXAMPLE	F2	0.015	0.20	0.5	0.006	0.004	0.011	8.3
A88	EXAMPLE	F4	0.015	0.15	0.4	0.006	0.004	0.011	13.1
A89	EXAMPLE	F2	0.015	0.20	0.5	0.006	0.004	0.011	8.1
A90	EXAMPLE	F4	0.015	0.15	0.4	0.006	0.004	0.011	13.3
A91	EXAMPLE	F2	0.010	0.15	0.3	0.006	0.004	0.011	8.3
A92	EXAMPLE	F2	0.010	0.30	0.4	0.006	0.004	0.011	8.3
A93	EXAMPLE	F2	0.030	0.15	0.3	0.006	0.004	0.011	9.0
A94	EXAMPLE	F2	0.030	0.30	0.4	0.006	0.004	0.011	8.3
A95	EXAMPLE	F4	0.025	0.20	0.5	0.006	0.004	0.011	13.3
A96	EXAMPLE	F4	0.020	0.10	0.4	0.006	0.004	0.011	13.3
A97	EXAMPLE	F4	0.035	0.25	0.6	0.006	0.004	0.011	13.3
A98	EXAMPLE	F4	0.025	0.15	0.4	0.006	0.004	0.011	13.3
A99	EXAMPLE	F4	0.015	0.15	0.4	0.006	0.004	0.011	13.3
A100	EXAMPLE	F3	0.030	0.05	0.4	0.006	0.004	0.011	12.5
A101	EXAMPLE	F3	0.030	0.08	0.4	0.006	0.004	0.011	12.8
A102	EXAMPLE	F3	0.030	0.11	0.4	0.006	0.004	0.011	13.1
A103	EXAMPLE	F3	0.030	0.08	0.4	0.006	0.004	0.011	13.3
A104	EXAMPLE	F3	0.030	0.12	0.4	0.006	0.004	0.011	13.5
A105	EXAMPLE	MILD STEEL	0.020	0.11	0.4	0.006	0.004	0.011	13.1
A106	EXAMPLE	F1	0.020	0.08	0.4	0.006	0.004	0.011	13.3
A107	EXAMPLE	F4	0.010	0.20	0.5	0.006	0.004	0.011	13.3
A108	EXAMPLE	F4	0.015	0.05	0.4	0.006	0.004	0.045	13.4

TABLE 3-12

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]									SM (%)	Ceq (%)
	Cu	Cr	Mo	V	Ti	Nb	B	Mg	REM
A82	0.3	0.1	0.2	0.12						0.70	0.523
A83	0.2			0.10	0.02					0.70	0.419
A84		0.1	0.2					0.2		0.90	0.500
A85	0.2	0.1	0.1	0.05	0.02		0.002			0.70	0.350
A86	0.2									0.55	0.420
A87	0.2		0.2	0.05				0.3		0.70	0.368
A88	0.2				0.02					0.55	0.415
A89	0.2							0.4		0.70	0.309
A90	0.2				0.02		0.002			0.55	0.420
A91		0.1	0.1							0.45	0.319
A92	0.2	0.2				0.01				0.70	0.337
A93	0.2			0.05						0.45	0.315
A94			0.2							0.70	0.367
A95	0.2			0.06	0.02					0.70	0.453
A96					0.02				0.050	0.50	0.423
A97	0.2	0.2	0.1						0.010	0.85	0.503
A98	0.1				0.02				0.001	0.55	0.430
A99										0.55	0.420
A100					0.02			0.5		0.45	0.411
A101					0.02					0.48	0.420
A102					0.02			0.3	0.020	0.51	0.429
A103					0.02					0.48	0.433
A104					0.02			0.4		0.52	0.439
A105					0.02			0.3		0.51	0.419
A106					0.01			0.3		0.48	0.423
A107	0.2									0.70	0.434
A108	0.1				0.07			0.6	0.020	0.45	0.419

TABLE 3-14

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]									SM (%)	Ceq (%)
	Cu	Cr	Mo	V	Ti	Nb	B	Mg	REM
B52										0.55	0.430
B53					0.02					0.35	0.397
B54				0.04				0.4		0.70	0.447
B55										0.70	0.444
B56	0.2									0.65	0.430
B57					0.02					0.65	0.430
B58								0.2		0.70	0.454
B59	0.2			0.05				0.4		0.65	0.438
B60					0.03					0.65	0.435
B61	0.2									0.70	0.454
B62										0.70	0.454
B63	0.2	0.2			0.02					0.65	0.327
B64		0.2	0.2							0.65	0.471
B65	0.2				0.02					0.33	0.364
B66				0.05						0.76	0.385
B67	0.3			0.03						0.40	0.339
B68	0.2					0.02		0.2		1.00	0.462
B69		0.1	0.1		0.02					0.80	0.471
B70	0.2			0.04						0.80	0.429
B71			0.2			0.02	0.003			0.50	0.416
B72		0.1		0.04						0.50	0.389
B73			0.1		0.02			0.2		0.60	0.253
B74	0.6	0.1								0.75	0.421
B75		0.6			0.03					0.65	0.505
B76			0.6		0.02			0.2		0.45	0.514
B77	0.3			0.30			0.003			0.70	0.416

TABLE 3-16

WIRE No.	CHEMICAL COMPOSITION OF FLUX [mass% WITH RESPECT TO TOTAL MASS OF WIRE]									SM (%)	Ceq (%)
	Cu	Cr	Mo	V	Ti	Nb	B	Mg	REM
B78	0.2				0.15					0.70	0.382
B79						0.15		0.4		0.70	0.382
B80	0.1	0.1	0.1				0.012			0.65	0.442
B81				0.05				0.7		0.65	0.401
B82	0.2	0.2			0.03					0.25	0.373
B83			0.1					0.4		1.10	0.468
B84	0.2					0.02				0.30	0.238
B85		0.3	0.4	0.15						0.90	0.533
B86	0.2		0.2				0.002			0.80	0.386
B87	0.2			0.08	0.02					0.95	0.368
B88			0.2					0.3		0.70	0.477
B89		0.1		0.03				0.2	0.055	0.55	0.398
B90				0.03						0.55	0.378
B91		0.1		0.03				0.2		0.70	0.421
B92										0.70	0.399
B93	0.2		0.1					0.1		0.55	0.410
B94					0.02					0.55	0.373
B95	0.1									0.75	0.424
B96	0.1									0.75	0.469
B97	0.1									0.45	0.499
B98		0.1	0.2					0.2		0.90	0.500
B99	0.2	0.1	0.1	0.05	0.02		0.002			0.70	0.350
B100	0.2									0.55	0.420
B101	0.2									0.55	0.400

TABLE 4-1

WIRE No.	CATEGORY	WELDING CONDITION
		CURRENT [A]	VOLTAGE [V]	WELDING RATE [cm/min]	HEAT INPUT [kJ/cm]	PREHEATING TEMPERATURE [°C]	INTERPASS TEMPERATURE [°C]	SHIELDING GAS	FLOW RATE [L/min]
A1	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A2	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A3	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A4	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A5	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A6	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A7	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A8	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A9	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A10	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A11	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A12	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A13	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A14	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A15	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A16	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A17	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A18	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A19	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A20	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A21	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A22	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A23	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A24	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A25	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A26	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25

TABLE 4-2

WIRE No.	CATEGORY	WELDING CONDITION
		CURRENT [A]	VOLTAGE [V]	WELDING RATE [cm/min]	HEAT INPUT [kJ/cm]	PREHEATING TEMPERATURE [°C]	INTERPASS TEMPERATURE [°C]	SHIELDING GAS	FLOW RATE [L/min]
A27	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A28	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A29	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A30	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A31	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A32	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.0%O2	25
A33	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.0%O2	25
A34	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.5%O2	25
A35	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.5%O2	25
A36	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A37	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A38	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A39	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A40	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	He	25
A41	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A42	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A43	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A44	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A45	EXAMPLE	280	25	30	14.0	50	150 OR LESS	Ar	25
A46	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A47	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.0%CO2	25
A48	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	He-1.0%O2	25
A49	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	He-1.0%CO2	25
A50	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A51	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A52	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A53	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A54	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A55	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25

TABLE 4-5

WIRE No.	CATEGORY	WELDING CONDITION
		CURRENT [A]	VOLTAGE [V]	WELDING RATE [cm/min]	HEAT INPUT [kJ/cm]	PREHEATING TEMPERATURE [°C]	INTERPASS TEMPERATURE [°C]	SHIELDING GAS	FLOW RATE [L/min]
A56	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A57	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A58	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A59	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A60	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A61	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A62	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A63	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A64	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A65	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A66	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A67	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A68	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A69	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A70	EXAMPLE	280	25	30	14.0	NONE	-50 OR LESS	Ar	25
A71	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A72	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A73	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A74	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A75	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A76	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A77	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A78	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A79	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A80	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A81	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A82	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A83	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A84	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A85	EXAMPLE	280	25	30	14.0	NONE	50 OR LESS	Ar-1.0%O2	25
A86	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.0%O2	25
A87	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.0%O2	25
A88	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.5%O2	25
A89	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.5%O2	25
A90	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.5%O2	25
A91	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-1.0CO2	25
A92	EXAMPLE	280	25	30	14.0	NONE	50 OR LESS	Ar	25
A93	EXAMPLE	280	25	30	14.0	NONE	50 OR LESS	He	25
A94	EXAMPLE	280	25	30	14.0	NONE	50 OR LESS	He-1.0%O2	25
A95	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	He-1.0%CO2	25
A96	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A97	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A98	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A99	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A100	EXAMPLE	280	25	30	14.0	50	150 OR LESS	Ar	25
A101	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A102	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A103	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A104	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A105	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A106	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar	25
A107	EXAMPLE	280	25	30	14.0	NONE	-50 OR LESS	Ar	25
A108	EXAMPLE	280	25	30	14.0	NONE	150 OR LESS	Ar-2.0%O2	25

TABLE 5-1

WIRE No.	CATEGORY	YIELD STRENGTH [MPa]	TENSILE STRENGTH [MPa]	CHARPY ABSORBED ENERGY AT -196°C [J]	AMOUNT OF OXYGEN IN WELD METAL[ppm]	Y-GROOVE WELD CRACKING TEST	AMOUNT OF DIFFUSIBLE HYDROGEN [ml/100g]	TENSILE STRENGTH	TOUGHNESS	COLD CRACKING RESISTANCE	OVERALL DETERMINATION	REMARKS
A1	EXAMPLE	675	721	60	94	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A2	EXAMPLE	669	709	61	104	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A3	EXAMPLE	687	736	63	97	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A4	EXAMPLE	672	725	60	102	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A5	EXAMPLE	720	766	52	109	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A6	EXAMPLE	719	778	50	89	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A7	EXAMPLE	616	662	68	99	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A8	EXAMPLE	769	828	54	90	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A9	EXAMPLE	682	733	61	96	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A10	EXAMPLE	700	745	57	105	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A11	EXAMPLE	671	716	63	93	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A12	EXAMPLE	706	752	53	93	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A13	EXAMPLE	699	740	62	87	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A14	EXAMPLE	685	736	59	99	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A15	EXAMPLE	626	695	67	104	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A16	EXAMPLE	728	793	56	90	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A17	EXAMPLE	716	772	58	105	NO CRACKING	1.4	PASS	PASS	PASS	PASS
A18	EXAMPLE	720	786	56	93	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A19	EXAMPLE	742	794	59	82	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A20	EXAMPLE	724	779	60	94	NO CRACKING	0.3	PASS	PASS	PASS	PASS
A21	EXAMPLE	749	802	55	88	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A22	EXAMPLE	726	782	57	97	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A23	EXAMPLE	744	791	54	95	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A24	EXAMPLE	703	743	61	100	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A25	EXAMPLE	727	760	58	106	NO CRACKING	0.7	PASS	PASS	PASS	PASS

TABLE 5-5

WIRE No.	CATEGORY	YIELD STRENGTH [MPa]	TENSILE STRENGTH [MPa]	CHARPY ABSORBED ENERGY AT -196°C [J]	AMOUNT OF OXYGEN IN WELD METAL[ppm]	Y-GROOVE WELD CRACKING TEST	AMOUNT OF DIFFUSIBLE HYDROGEN [ml/100g]	TENSILE STRENGTH	TOUGHNESS	COLD CRACKING RESISTANCE	OVERALL DETERMINATION
A56	EXAMPLE	654	708	93	62	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A57	EXAMPLE	652	695	97	51	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A58	EXAMPLE	693	730	89	65	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A59	EXAMPLE	690	736	92	56	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A60	EXAMPLE	751	796	84	55	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A61	EXAMPLE	763	802	72	75	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A62	EXAMPLE	620	665	95	53	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A63	EXAMPLE	757	828	79	59	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A64	EXAMPLE	692	744	88	55	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A65	EXAMPLE	687	732	85	69	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A66	EXAMPLE	706	751	90	65	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A67	EXAMPLE	685	736	73	57	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A68	EXAMPLE	723	784	84	68	NO CRACKING	0.9	PASS	PASS	PASS	PASS
A69	EXAMPLE	729	790	79	63	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A70	EXAMPLE	746	796	78	64	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A71	EXAMPLE	735	786	80	55	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A72	EXAMPLE	722	769	84	54	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A73	EXAMPLE	734	777	80	55	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A74	EXAMPLE	721	784	77	59	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A75	EXAMPLE	719	769	93	42	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A76	EXAMPLE	735	782	77	56	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A77	EXAMPLE	749	794	88	49	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A78	EXAMPLE	723	771	80	64	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A79	EXAMPLE	745	789	79	65	NO CRACKING	0.5	PASS	PASS	PASS	PASS

TABLE 5-6

WIRE No.	CATEGORY	YIELD STRENGTH [MPa]	TENSILE STRENGTH [MPa]	CHARPY ABSORBED ENERGY AT -196°C [J]	AMOUNT OF OXYGEN IN WELD METAL[ppm]	Y-GROOVE WELD CRACKING TEST	AMOUNT OF DIFFUSIBLE HYDROGEN [ml/100g]	TENSILE STRENGTH	TOUGHNESS	COLD CRACKING RESISTANCE	OVERALL DETERMINATION
A80	EXAMPLE	681	720	86	59	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A81	EXAMPLE	669	712	94	55	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A82	EXAMPLE	701	743	88	64	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A83	EXAMPLE	724	764	82	58	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A84	EXAMPLE	764	805	78	65	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A85	EXAMPLE	712	752	79	68	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A86	EXAMPLE	694	735	80	63	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A87	EXAMPLE	697	739	84	65	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A88	EXAMPLE	695	740	75	75	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A89	EXAMPLE	659	722	72	78	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A90	EXAMPLE	666	726	73	76	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A91	EXAMPLE	659	715	92	54	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A92	EXAMPLE	671	724	87	59	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A93	EXAMPLE	723	778	76	63	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A94	EXAMPLE	729	789	79	60	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A95	EXAMPLE	719	760	82	63	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A96	EXAMPLE	702	765	79	70	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A97	EXAMPLE	775	895	71	65	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A98	EXAMPLE	692	798	82	56	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A99	EXAMPLE	687	745	80	61	NO CRACKING	0.5	PASS	PASS	PASS	PASS
A100	EXAMPLE	708	786	78	68	NO CRACKING	0.4	PASS	PASS	PASS	PASS
A101	EXAMPLE	670	742	84	78	NO CRACKING	0.8	PASS	PASS	PASS	PASS
A102	EXAMPLE	658	752	72	76	NO CRACKING	0.7	PASS	PASS	PASS	PASS
A103	EXAMPLE	663	774	95	72	NO CRACKING	0.8	PASS	PASS	PASS	PASS
A104	EXAMPLE	710	831	79	76	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A105	EXAMPLE	620	743	68	82	NO CRACKING	0.9	PASS	PASS	PASS	PASS
A106	EXAMPLE	643	782	78	72	NO CRACKING	1.0	PASS	PASS	PASS	PASS
A107	EXAMPLE	705	738	62	95	NO CRACKING	0.6	PASS	PASS	PASS	PASS
A108	EXAMPLE	663	694	69	79	NO CRACKING	0.6	PASS	PASS	PASS	PASS

TABLE 6

BASE METAL No.	PLATE THICKNESS [mm]	CHEMICAL COMPOSITION OF STEEL PLATE [mass%]											MECHANICAL PROPERTY
		C	Si	Mn	P	S	Ni	Al	Mo	N	O	Ceq	YIELD STRENGTH [MPa]	TENSILE STRENGTH [MPa]	CHARPY ABSORBED ENERGY AT -196°C [J]
P1	25	0.06	0.2	0.6	0.002	0.001	9.12	0.04	0.01	0.004	0.001	0.40	675	725	178
P2	20	0.06	0.2	0.5	0.006	0.004	9.25	0.02	0.01	0.004	0.001	0.38	669	720	197

[Industrial Applicability]

[0129] The gas-shielded arc welding capable of significantly reducing welding material costs and achieving excellent welding efficiency can be applied by reducing the amount of Ni of the flux-cored wire used for welding Ni-based steel for low temperature use containing about 5.5% to 9.5% of Ni to the same level as Ni-based steel for low temperature use. In addition, a weld metal having excellent low temperature toughness at -196°C can be obtained by reducing the alloy composition of the flux filled in the wire to reduce the amount of oxygen in the weld metal. Further, it is possible to provide a flux-cored wire in which preheating for preventing cold cracking is not required or preheating can be significantly reduced. Therefore, the industrial value of the present invention is very high.

[Brief Description of the Reference Symbols]

[0130] 

1:

STEEL PLATE

2:

BACKING METAL

3:

WELD BEAD

4:

CHARPY IMPACT TEST PIECE (HAVING 2 MM V-NOTCH)

5:

A0 TEST PIECE (ROD) FOR TENSILE TEST

Claims

1. A flux-cored wire for gas-shielded arc welding comprising:

an outer steel sheath; and

a flux with which the outer steel sheath is filled,

wherein one or more of CaF₂, BaF₂, SrF₂, MgF₂, and LiF, which are metal fluorides, are included in the flux-cored wire and, when a total amount thereof is defined as α, the α is 2.0% to 7.0%, by mass%, with respect to a total mass of the flux-cored wire,

one or more of a Ti oxide, a Si oxide, a Mg oxide, an A1 oxide, a Zr oxide, and a Ca oxide, which are metal oxides, are included in the flux-cored wire and, when a total amount thereof is defined as β, the β is 0.2% to 0.9%, by mass%, with respect to the total mass of the flux-cored wire,

one or more of CaCO₃, BaCO₃, SrCO₃, MgCO₃, and Li₂CO₃, which are metal carbonates, are included in the flux-cored wire and a total amount thereof is less than 0.6%, by mass%, with respect to the total mass of the flux-cored wire,

a ratio of an amount of the CaF₂ with respect to the α is 0.90 or more,

a ratio of the α with respect to the P is 3.0 or more and 15.0 or less,

an amount of the Ti oxide is 0% to 0.4%, by mass%, with respect to the total mass of the flux-cored wire,

an amount of the Si oxide is 0.2% to 0.5%, by mass%, with respect to the total mass of the flux-cored wire,

an amount of the Ca oxide is less than 0.20%, by mass%, with respect to the total mass of the flux-cored wire,

an amount of an arc stabilizer in the flux is 0% to 0.50%, by mass%, with respect to the total mass of the flux-cored wire,

an amount of an iron powder in the flux is less than 5%, by mass%, with respect to the total mass of the flux-cored wire,

chemical compositions except the metal fluorides, the metal oxides, and the metal carbonates include, by mass%, with respect to the total mass of the flux-cored wire,

C: 0.003% to 0.040%;

Si: 0.05% to 0.40%;

Mn: 0.2% to 0.8%;

Al: 0.003% to 0.050%;

Ni: 6.0% to 16.0%;

P: 0.02% or less;

S: 0.01% or less;

Cu: 0% to 0.5%;

Cr: 0% to 0.5%;

Mo: 0% to 0.5%;

V: 0% to 0.2%;

Ti: 0% to 0.1 %;

Nb: 0% to 0.1 %;

B: 0% to 0.01 %;

Mg: 0% to 0.6%;

REM: 0 to 0.0500%; and

a remainder: Fe and an impurity,

a SM defined by the below expression a is 0.3% to 1.0%,

a Ceq defined by the below expression b is 0.250% to 0.525%,

in the Expressions a and b, elements noted in brackets express amounts (mass%) of the elements, respectively.

2. The flux-cored wire for gas-shielded arc welding according to claim 1, wherein the flux-cored wire includes the outer steel sheath including Ni and the flux filled therein, and
an amount of Ni in the outer steel sheath is 6% to 18%, by mass%, with respect to the total mass of the outer steel sheath.

3. The flux-cored wire for gas-shielded arc welding according to claim 1 or 2, wherein an amount of REM in the flux-cored wire is 0.0100% or less, by mass%, with respect to the total mass of the flux-cored wire.

4. The flux-cored wire for gas-shielded arc welding according to any one of claims 1 to 3, wherein the amount of the CaO as the Ca oxide in the flux-cored wire is less than 0.10%, by mass%, with respect to the total mass of the flux-cored wire.

5. The flux-cored wire for gas-shielded arc welding according to any one of claims 1 to 4, wherein a tensile strength of a weld metal is 660 MPa to 900 MPa in a tensile test to the weld metal regulated in Japanese Industrial Standards JIS Z 3111-2005 in the gas-shielded arc welding using the flux-cored wire.

6. The flux-cored wire for gas-shielded arc welding according to any one of claims 1 to 5, wherein a slit-shaped gap does not exist in the outer steel sheath of the flux-cored wire.

7. The flux-cored wire for gas-shielded arc welding according to any one of claims 1 to 5, wherein a slit-shaped gap exists in the outer steel sheath of the flux-cored wire.

8. The flux-cored wire for gas-shielded arc welding according to any one of claims 1 to 7, wherein a perfluoropolyether oil is applied on a surface of the outer steel sheath of the flux-cored wire.

9. A method for welding steel for very low temperature use, wherein welding is performed with the flux-cored wire for gas-shielded arc welding according to any one of claims 1 to 8, and with any one of a pure Ar gas, a mixed gas of Ar and 1.5 volume% or less of O₂ or CO₂, a pure He gas, and a mixed gas of He and 1.5 volume% or less of O₂ or CO₂ as a shielding gas.

10. A method for manufacturing a weld joint, wherein a steel plate in which a thickness is 6 mm to 100 mm, an amount of Ni is 5.5 mass% to 9.5 mass%, and a tensile strength is 660 MPa to 900 MPa is welded with the flux-cored wire for gas-shielded arc welding according to any one of claims 1 to 8, and with any one of a pure Ar gas, a mixed gas of Ar and 1.5 volume% or less of O₂ or CO₂, a pure He gas, and a mixed gas of He and 1.5 volume% or less of O₂ or CO₂ as a shielding gas.

Drawing